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Primoris Prognatus







Technology Level

Tier 1






198.1–414 cm (6 ft 6 in–13 ft 7 in)


109.8–377.1 kg (242–831.4 lbs)


Thousands of years

Distinctive traits

Tall bipedal humanoids, partially furred; various forms assumed depending on Caste; access to incredibly advanced technologies including sophisticated armor


Mostly Extinct

"One hundred thousand years ago, the galaxy was populated by a great variety of beings. But one species—eons beyond all the others in both technology and knowledge—achieved dominance. They ruled in peace but met opposition with quick and brutal effectiveness. They were the Forerunners—the keepers of the Mantle, the next stage of life in the Universe's Living Time."

The Forerunners (Latin Primoris prognatus, meaning "Firstborn") were an ancient species of technologically advanced beings who originally dominated the Milky Way Galaxy, their Ecumene Empire holding all the stars of the galaxy in their grasp. They reigned for thousands of years as the dominant species until the arrival of the Flood, a hyper-virulent parasitic race that sought to consume all life. Despite their technological superiority, the Forerunners quickly lost much of their territory to the parasite, and billions of lives were lost to the Flood's vastly overwhelming numbers. This forced the Forerunners to employ a sacrificial, suicidal tactic of exterminating all life in the galaxy to halt the advance of the Flood, thus creating the Halo Array to deprive the parasite of their source of biomass. The Forerunners extracted select numbers of surviving species to be safeguarded outside the firing range before activating the rings, killing every living thing still in the Milky Way, including themselves, but successfully starving out the Flood into dormant hybernation. The remaining Forerunners then re-seeded the Galaxy with the surviving sample species so that life could propegate again before going into eternal exile. Although essentially extinct, evidence of the Forerunners were left behind on thousands of worlds as well as their own installations, spread across the Milky Way for others to find.



Around 15,000,000 BCE, the Forerunners were created by the Precursors, a primordial race of supreme beings, on the planet Ghibalb, located within the Orion Complex of the Milky Way Galaxy. The Forerunners were among countless other species created by the Precursors, though were slated to be superior to all other life so they would one day inherit the Mantle of Responsibility, an ideology to guide the security and development of life so that the Precursors could live in comfortable exile. The Precursors did not alone create the Forerunners for this purpose, also developing a second race, Humanity, to take the Mantle.

They grew as a species and developed incredible technologies from the gifts granted by the Precursors, even settling on worlds located within twelve nearby planetary systems. The Forerunners eventually acquired supremely powerful interstellar capabilities, and began to colonize the entirety of the Orion Complex. However, Ghibalb suffered tremendously during an experiment in stellar engineering; the Forerunners accidentally caused several nearby stars to go supernova, wiping out all life in their home star system and damaging the planets. Ghibalb became heavily irradiated and uninhabitable, forcing the Forerunners to establish a new main home on another world.

Usurping the Mantle[]

After recovering from the loss of their home star system, the Forerunners expanded further to encompass a much larger area of space. They came to dominate the Orion Complex, developing their technology to outstanding Interstellar capabilities; as they developed, the Forerunners came to believe they would be judged worthy to be the inheritors of the Mantle. However, the Precursors decided to pass the Mantle down to Humans instead, seeing their less reckless development of power and a lesser ambition to dominate while possessing an unseen compassion the Forerunners ultimately lacked.

Provoked by this revelation, the Forerunners responded by rising up against their creators, and used their incredible technological gifts passed down to them against the Precursors themselves. Despite the Precursor's superior understanding of universal principles and technological prowess, they were caught off-guard by the ferocity of the Forerunners, led by the then-dominant Warrior Rate, and systematically exerminated as the Forerunners continued to expand from the Orion Complex and spread across the Core Worlds of the Milky Way Galaxy. The Forerunners succeeded in overthrowing their creators, exterminating almost every last one of them in retaliation to the rejection of the Forerunners as being worthy of the Mantle.

The Warriors would chase the Precursors out of the Milky Way to Path Kethona, a satellite galaxy later known as the Large Magellanic Cloud. Save for a few Precursors that managed to elude them, the Forerunners wiped out the last of their creators and assumed the Precursors finally destroyed. Some of the Forerunners questioned the ethics of the genocide and refused to take part; many were executed themselves, while others escaped and went into exile on a barren planet. To avoid detection, they rid themselves of their technology and humbled themselves to a simple way of primative living once they were left behind by the Warriors. They continued to survive for millions of years, preserving the knowledge of their true origins in a biological reservoir of ancestral memory.

Ultimately, the exiles were the only survivors of those that departed the Milky Way to eradicate the Precursors; the Warriors who carried out the executions were unable to make it back, dying out and never returning to their home galaxy.

Early history[]

History Rewritten[]

Following the erradication of the Precursors, the Warrior Rate altered history to the Forerunner's benefit. According to the new official knowledge, the Precursors simply disappeared soon after creating the Forerunners on their original homeworld, leaving them behind to inherit the Mantle of Responsibility while also erasing knowledge of the Humans from the Forerunner archives. Thus, the rebellion was forgotten over time, leaving the Forerunners to believe they alone were intended to assume guardianship of all life. A few in high positions of the Warrior and Builder Rates retained the truth, though they kept it from public discovery to maintain the sense of Forerunner superiority. Anyone that managed to uncover the truth were systematically executed quietly to prevent the information from leaking.

The Forerunners spread throughout the core worlds of the Milky Way, taking advantage of the incredible number of stars to establish thousands of new colonies before making it the center of their empire.

Core Expansion[]

To protect their newly established territory, the Forerunners constructed the Maginot Line, an immense array of defensive installations spread out in a sphere surrounding the galactic core. This defense was meant to repel any potential large or small-scale attack should the Forerunners be forced to abandon the greater majority of their projected empire worlds in the outer galaxy.

Galactic Dominion[]

Having secured the Galactic Core as their new home, the Forerunners used the area as a base to initiate a mass colonization effort to take the rest of the galaxy, spreading out among the inner, mid, then finally the outer rims until ultimately everything was in their control.

Around 150,000 BCE, Humanity had finally began moving away from their homeworld and founded an interstellar civilization of their own. The Forerunners largely ignored them but kept an eye on the Humans in the event they became a problem.

During the spread of the Ecumene Empire throughout the Galaxy, the Forerunners created a large space installation to serve as their main seat and capital for their galactic empire. This Capital, also known as Maethrillian, was built around 122,445 BCE and came to house the Ecumene Council as well as a large number of other Forerunners living there.

Kradal Conflicts[]

A short-term civil conflict in the Galactic Core sprung in the Forerunner Empire, which would be known as the Kradal Conflict or the Kradal Conflicts. The oppression was ultimately put down, though cost many lives.

War with Humanity[]

A battle between Forerunners and Humans

Around 107,445 BCE, the Forerunners went to war with humanity's interstellar empire in response to a perceived invasion of Forerunner worlds. This invasion was thought to be caused by both human resentment at Forerunner expansionism during the previous fifty years and by the rapid growth of human populations. The true cause of the invasion was actually a desperate attempt to migrate humans away from an extragalactic threat which would later plague the Galaxy, though the Forerunners had no knowledge of this for quite some time.

The Forerunners perceived humanity's actions to be a threat to the principles of the Mantle, and therefore waged a decisive war against the Humans. The Humans proved themselves to be close to equal to the Forerunner's capabilities of war, managing to last a few years in a number of initial successes against the Forerunners. The Humans were even able to push back against the extragalactic threat and were cast beyong the edge of the Galaxy, saving the Humans from their plight; however, this cost them much-needed resources to fight the Forerunners, exhausting themselves and being left open for the Forerunner retaliation. Even though the Humans sided with another advanced race, the early San-Shyuum, they proved unable to stop the advance of the Forerunners. The Forerunner Warriors began subjugating every Human world and wiping them clean of civilization upon defeating the military forces. Eventually, the Humans were siezed at their last world, the capital of Charum Hakkor, and ultimately surrendered to the Didact, the leader of the Forerunner Warrior Rate.

As punishment for the Human invasion, the Forerunners stripped Humanity of their empire and technology, exiling them to their original home-world Erde-Tyrene, later known as Earth. The Forerunners devolved the Humans, splintering them among separate collective kinds and forced to start over as a primitive race. The Forerunners also deprived the San-Shyuum of their technology and similarly devolved and isolated them on their homeworld, Janjur Qom.

Relative Peace[]

Following the events of the war with Humanity, an investigation on their motives for invasion uncovered the truth of an outside hostile threat. A select group of Councilors and elite Forerunners turned their attention to the possibility of the return of said threat, while keeping the information out of public knowledge to prevent a panic. The Didact advocated a policy of watchfulness and military readiness, proposing a plan to construct a fleet of hundreds of artificial planets known as Shield Worlds to provide rapid military support and shelter for mass populations. An opposing plan was drafted by the Master Builder, instead suggesting the construction of an array of serilizing superweapons that would operate on a huge scale as the ultimate defense. The Council favored the Builder's proposal, causing the prominent Forerunner Lifeworker and wife of the Didact known as the Librarian to speak out against the Builder's proposal of genocide. This had the Council allow the Lifeworker Rate to work on the project as well, collecting samples of life to be preserved on the array to preserve them in a plan known as the Conservation Measure. This also constituted the construction of a new massive megastructure in space, known as the Ark, in the event the Forerunners were forced to evacuate their Empire.

At the same time, she could not prevent the punishment of the Warriors, which was organized by the Builders in an effort to secure themselves as the leaders of Forerunner society. In retaliation for the perceived wanton extermination of Humanity as well as their favor of the Shield World measure, the Didact and his Prometheans, the highest class Warriors directly supporting him, were exiled from their positions of power while the rest of the Warrior Rate was marginalized over the next thousand years. Their fleets and armies were merged into Builder-Security, ultimately decreasing their value and skill as raw soldiers and leaving the Empire ill-prepared for the coming conflict.

Forerunner-Flood War: Beginnings[]

Around 100,000 BCE, the extragalactic threat began their return to the Milky Way Galaxy, believed to originate from the Large Magellanic Cloud. They slowly filtered in to the outer rim edge, mostly evading detection while spreading among many star systems and making landfall on several planets.

The first contact the Forerunners had with the threat was on the outer colony of G617-g1 around 97,745 BCE. The colony was completely overwhelmed and all life on the world was lost. Similar events began to occur on hundreds of other worlds nearby, all across the edge of the Forerunner's empire towards the Large Magellanic Cloud. The sheer number of the threat, revealed to be of a parasitic nature, overwhelmed naval defense forces before they could be repelled and costing the lives of billions of Forerunners and others on these planets. This parasite was referred to as the Flood.

To prevent a panic, any knowledge of the Flood was greatly limited by the Builders; the infection proposed as simply a mutation-inducing disease caused by stellar radiation. As the Flood grew in number and became more intelligent in the process, the Forerunner military forces were ordered to don heavy armor and other personnel were ordered into protective stasis. Flood were taken into M-type Installations and studied in an effort to find yet another countermeasure. The Forerunners were able to identify a centralized intelligence coordinating their assault: the Gravemind, the collective hive-mind conciousness of the Flood itself which manifested itself throughout the entire parasite in the millions of Flood forms quickly spreading across space. The Forerunners employed numerous strategies to combat the Flood; one effort included sacrificing Keyships in costly naval tactics to draw the Flood into mutual destruction, though such efforts succeeded on too much of a small scale to prove effective.

Another strategy involved the use of the Composer, a machine originally designed to allow the Forerunners to transcend their physical form to exist as entities of data. The Builders tested the Composer's ability to cure victims of Flood infection, predicting its erasure of biological form would wipe away traces of infection while preserving the essences of the victims to be restored in a new, clean physical form. Unfortunately, this was a flawed process as anyone treated with the Composer suffered a decay of essence and gruesome death, while attempts to restore essences to physicality resulted in horrific, monstrous mutations that had to be put down to end sufferings. The Composer was subsequently abandoned.

The Ecumene realized the only viable strategy was to stop the flow of the Flood before they could access more biomass; referring to the genocidal tactics of the Builders, the Fleet began to use orbital bombardment on colonies upon Flood arrival to slow the spread, though such small-scale tactics barely had any effect on the parasite. The planetary bombardment turned into complete system-wide destruction as their despiration grew, causing stars to go supernova to erradicate whole planetary systems. Though the option of using the Halo Array existed, the Forerunners postponned any use of them as a very last resort. As the Forerunners developed other strategies instead, the Flood were able to overcome them and best seasoned Forerunner commanders, resulting in further loss of life while increasing the numbers of the Flood.

Forerunner-Flood War: Initial Forestalling[]

The Forerunners were able to contain the spread of the Flood momentarily after they developed the first Contendor-class AI, dubbed Mendicant Bias, leading to a brief stalemate in the conflict. Mendicant Bias's superior strategy capabilities were able to forestall the Flood advance for a moment, leading the Forerunners into a false sense of security; however, this was actually due to a temporary lull in the Flood effort as they came up with a way to turn the AI against their creators.

As a precautionary measure, the Builders ordered Mendicant Bias to test-fire Installation 07 at Charum Hakkor as a demonstration of its refined effectiveness. This resulted in the release of the Primordial, an entity confined on the world who was interrogated by the Didact for information long ago. The Master Builder then charged Mendicant Bias with transporting the entity on Installation 07 where it would interrogate the creature. He moved the Installation to a hidden area for his own unsanctioned experiments.

During the 43-year long conversation, the Primordial ultimately turned Mendicant Bias against the Forerrunners to support the Flood instead, turning the AI rampant from exposure to the Logic Plague. Mendicant Bias released the Primordial from its prison and disappeared with it from Installation 07. Unaware of this, the Master Builder dispatched Installation 07 to Janjor Qom and activated it to suppress a San'Shyuum uprising. As this was a clear violation of the Mantle, the Ecumene Council annexed support of the Builder Guild while gathering their Halo Array to the Capital Maethrillian to be decommissioned, seeing their use as being too extreme.

However, Mendicant Bias arrived aboard Installation 07 and seized command of the Array, firing the Array on the Capital and erradicating many of the Forerunners present before they could stop him. Shortly after the crippling of the Capital, the remaining Forerunner higher-ups and primary fleet met up elsewhere. As a new Council was formed, the IsoDidact presented himself before them as a copy of the original Didact, who had recently returned from his exile but was captured and abandoned by the Master Builder before the loss of the Capital. The IsoDidact assumed command of the Forerunner military, and revealed his plan to return to conventional strategy by reactivating the Shield Worlds left behind long ago.

Forerunner-Flood War: Turn of the Tide[]

Mendicant Bias' defection and decapitation of the Old Council marked the turning point in the war; what had been a steadily growing but relatively contained infection had become a rapidly expanding wildfire, exploding beyond hope of control. The Flood began to strike critical Forerunner systems in overwhelming numbers using vessels and forces by both infected personnel and other AI turned rampant by the Logic Plague, quickly overpowering any Forerunner forces assembled to defend planetary systems. The number of planets entirely consumed by the Flood began to number in the hundreds of thousands, manifesting as homes to entire Flood Hives whose intelligence rivalled even those of the most powerful Forerunner AIs.

The majority of surviving Forerunners were evacuated to the safety of the Maginot Line which were able to protect their Core Worlds for a time. The new Forerunner Council essentially abandoned the rest of the Galaxy to fend for themselves while hiding in the protection of the Core systems. Though the Flood breached the Line in several locations, the defense was able to hold up until the very end of the war. During this time, the Librarian and her Lifeworkers traveled beyond the line, risking themselves tremendously in order to index and gather surviving species for preservation at the Ark, while the IsoDidact commanded Forerunner defense operations and offensive strikes from within the Line, marking a return of the Warriors as a separate Rate while receiving aid from the defunct Builder Security.

In this late stage of the war, the Flood became powerful enough to use nerual physics-based technology, allowing them to take control of the numerous Precursor artifacts which were left behind for millions of years following their disappearance, such as Star Roads. The Forerunners did not possess any formidable defense against the sheer power and destructive capability of the Precursor constructs, which were capable of effortlessly dealing widespread devastation on entire Forerunner fleets. After disabling their weapons and shields, the star roads corralled Forerunner vessels into smaller units to allow their crews to be parasitized by the Flood. Less than one half of one percent of Forerunner vessels attacked this way were able to self-destruct before they were overwhelmed. The Precursor constructs were also capable of manipulating space-time to become unsuitable for Forerunner slipspace travel and leaving entire fleets stranded or lost in anomalous slipspace transit. During this time, entire planets committed planet-wide mass suicide to deprive the Flood access to their biomass as potential hosts. The Flood would then leave the dead world untouched as there was nothing of interest on the planet for them, leaving the intact Forerunner cities behind.

Final Assaults[]

Having evacuated the remaining Forerunner population to safety, Forerunner fleets were repositioned to defend four regions of the Inner Rim, which was nearly overwhelmed by the Flood. Despite attaining a rare victory at one of these regions, the Forerunners continued to lose ground in most engagements. The Forerunners would develop a replacement for Mendicant Bias to help defend the last sectors of space; a Metarch-class AI dubbed Offensive Bias, which was more limited in creativity but was hoped to be less vulnerable to the Flood as a result. The design of the AI was overseen by the IsoDidact, who worked closely with its development and conditioning to ensure its loyalty.

The Ur-Didact preparing to battle the Flood

Meanwhile, the original Ur-Didact had returned from his isolation thanks to a rescue by the Master Builder. In spite of his return, the remains of the Ecumene favored the IsoDidact, though the Ur-Didact was restored to his position and the IsoDidact would support his strategies. In secret, the Ur-Didact recovered the Composer, and subjected himself to a series of mutations in an effort to render himself immune to the Flood. After he failed and also realized the Composer would not work on him either, his loyal Prometheans volunteered themselves to its effects so he could command a mechanical army immune to the Flood. After mass-composing all but one of his Prometheans, the Ur-Didact lead a campaign of small strikes against Flood fleets; though effective on a small scale, his original number of Prometheans were not enough to stop the Flood entirely, leaving him to seek out more victims to replace those that were destroyed in combat.

In a decisive last stand, the last combined Forerunner fleet outside the Inner Rim faced massive swarms of infected ships, supported by thousands of star roads. With the defenses of the Inner Rim beseiged by the Flood, strategic command of the Ecumene was placed in the Ark. The Librarian's recovered specimens, including her main repository of Humans, were moved to Omega Halo, the last of the original Halos still in Forerunner control as the others were destroyed or assimilated in Installation 07's case.

A handful of Forerunner military commanders survived to retreat to the greater Ark, managing to bring a small number of warships with them to defend what was now the ecumene's last bastion. The remaining Forerunner leadership gathered here, including the Ur-Didact. Soon after their arrival, the Ark came under siege by Mendicant Bias and its fleet of Flood-controlled ships and star roads. Out of desperation, the remnants of the Council restored the Master Builder to command, as he was the only one with a realistic vision on how to stop the Flood: a new Halo Array, which could target all neural structures—including the Flood's Precursor structures, thus capable of stopping them once and for all. Thus, he revealed the location of one of his most closely guarded secrets: a secondary Ark which would be used to house survivors and forge another Array of Halos.

The second-to-last major battle of the war involved the original, Greater Ark and Omega Halo. Immediately prior to the battle, the Omega Halo was struck by the Ur-Didact, who was driven mad by the Gravemind in his isolation. He had recovered the Composer and used it to digitize the entire human population stored on the Halo, to the horror of the Librarian and all other witnesses. His plan involved harnessing the essences to replace the losses incurred on his Promethean army. Shortly after his departure, the Flood arrived, forcing the Forerunners to fire the Omega Halo, pointing its weapon to tear a hole in the approaching Flood wave and striking the Large Magellanic Cloud despite the incredible intergalactic distance; the Flood quickly recovered despite a desperate defense by Offensive Bias, as their fleet destroyed the Omega Halo and the Greater Ark. The Master Builder was among those who lost their lives. The IsoDidact, Monitor Chakas, and some other survivors headed to the Lesser Ark, taking with them what biological specimens they managed to evacuate from the Greater Ark. Meanwhile, Offensive Bias took a significant force of Forerunner ships to return to the Core Worlds and resecure the fragmented Maginot Line.

Following this catastrophe, the Librarian was greatly displeased and overwhelmed with grief and fury at the Ur-Didact's actions. As the Ur-Didact returned to his main fortress of Requiem, the Librarian pursued him to put a stop to his mad campaign. After convincing the last organic Promethean to stand aside, the Librarian confronted the Ur-Didact in private and subdued him, sealing him in his Cryptum to ponder his crimes and hopefully return to his senses. Leaving the Didact and his Prometheans behind on Requiem, she planned on him surviving the Flood war and leading Humanity to reclaim the Mantle of Responsibility once they recovered from the war.

The other Forerunners found and accessed a portal on Earth, which transported them to the hidden location of the Lesser Ark, outside the Galaxy away from the Flood's path from the Large Magellanic Cloud. The Librarian eventually followed after them, and all the survivors met on the Lesser Ark.

Activation of the Array[]

Upon arrival, the Forerunners gathered at the Citadel and observed the Master Builder's final contingency: the plans for the new Halo Array, smaller in size but more widespread in effect, and seeing predetermined locations for the Halos to be placed, calculated the entire Galaxy would be rendered sterile and finally stopping the Flood once and for all.

The IsoDidact began construction of the rings, though the approach of the Flood towards Earth threatened the infection of the Lesser Ark. To buy some time, Offensive Bias gathered what remained of the Forerunner defense fleet at the fractured Maginot Line, rebuilding its defenses in preparation for a final assault.

To ensure enough time for the Halo Array to fire, the IsoDidact ordered Offensive Bias and all that remained of the Forerunner fleets to delay Mendicant Bias' fleet. To this end, Offensive Bias alerted Mendicant Bias of supposed populations still within the Core Worlds. Thus, Mendicant Bias directed its primary force back towards the Line, though a secondary Flood wave still made its way towards Earth. While the IsoDidact deployed the seven Halo rings to their locations and initiated the Halo Array's activation sequence, the Librarian journeyed to Earth to ensure the Portal to the Ark closed. Ignoring the IsoDidact's pleas to return to the Ark, the Librarian calmly embraced her inevitable demise in the area which would later be known as Voi, observing the dissemination of her ship and the closure of the Portal to the Ark. 

Meanwhile, the Flood fleet engaged the last Forerunner fleet in the Battle of the Maginot Line. Feigning incompetence and using delaying tactics, Offensive Bias and his fleet held off the Flood as the Halos activated, exterminating all sentient life in the Milky Way galaxy. With the previously Flood-controlled ships now adrift, Offensive Bias annihilated Mendicant's remaining fleet within minutes. Offensive then proceeded to extract the last remaining shard of Mendicant Bias from one of its core ships and return it to the lesser Ark.


The Halo effect purged the galaxy of all sentient life, eliminating the threat of the Flood as it was deprived of available biomass and its collective consciousness. All Precursor artifacts and structures, composed of abstract neural physics construction, were likewise destroyed. These included the Domain, a metaphysical repository of knowledge treasured by the Forerunners as the source of all their cultural heritage and ancestral wisdom. The surviving Forerunners on the Ark, under the leadership of the IsoDidact, imprisoned what was thought to be the last component of Mendicant Bias deep within Installation 00. The lifeforms sheltered on the Ark were eventually returned to their homeworlds and reintroduced to their native ecosystems, now free of the Flood, by the remaining Forerunners and their automatons; this process was led by the new Lifeshaper, Chant-to-Green.

Despite the Lifeworkers' best efforts, the firing of the Halos resulted in mass extinction events on countless worlds across the galaxy; most prominently those the Forerunners had never had the time or resources to index. On many planets, Lifeworkers had to prioritize which species to save; for example, it was estimated that only one-thousandth of Earth's large species would survive. Around four years before the firing of the Halos, 123 technologically capable species had been indexed; however, a number of these were doomed to perish due to the Lifeworkers' limited resources, combined with the devastation of the preserves on the Greater Ark and Omega Halo. Many species also died out as a result of planetary ecosystems failing to properly recover after their reseeding, during the subsequent period known as the Dark Time.

In addition to restoring planets to some extent of life, the Forerunners also recovered great amounts of leftover Flood organisms, rendered dormant in deprived hybernation, and isolating them within various select and highly-secured laboratories aboard the Halo Rings and a few Shield Worlds, among other locations, for long-term analysis and study for potential weaknesses should the Flood return. However, they kept the Halos in place and on-line, in the event they would be needed once more if the Flood prooved too strong as they did before.

After this reseeding effort was finished the surviving Forerunners left the galaxy, vowing to exclude themselves from the affairs of other species out of guilt over their failure as galactic custodians. The Forerunners left the Mantle for Humanity to reclaim as the Precursors had intended millions of years earlier.


The Forerunners left behind a large number of artifacts and pieces of their advanced technology, intending for Humanity as a whole to recover them and Reclaim the Mantle of Responsibility, acquiring guardianship of all life in the wake of the Exile of the surviving Forerunners. The mystery of the artifacts and the fate of their owners lead many species across the Galaxy to come to recognize the Forerunners as symbols of worship and legend upon discovering the remains of their Empire.

Human-Covenant War[]

Though the Forerunners were long gone 100,000 years after the war with the Flood, their artifacts played an important role in future conflicts, notably the war between Humanity and the Covenant. A collection of alien species unified under a religious banner in worship of the Forerunners as Gods, the Covenant mistook the intentions of the Forerunners as having the desire to wipe out Mankind and activate the Halos once again in order to ascend to heaven with the Forerunners, though this was only due to the manipulation of truth by the High Prophets. Though other races, including Humans, also came across many pieces of evidence of previous Forerunner existence, Humanity remained largely unaware of the Forerunners until well into the war with the Covenant.

During the Human-Covenant War, the first Halo to be found by Man became the location of one of the most important battles in modern history. Taking place at Installation 04, the fight between the United Nations Space Command and the Covenant Empire released the Halo's store of captured Flood forms, forcing the Master Chief to destroy the Halo in order to contain the Flood.

Later on, the UNSC pursued the Prophet of Regret into deep space and found their second Halo, Installation 05. Another battle took place, though both sides realized the Flood was long ago released due to a containment breach and grew much worse by the time of their arrival. Most of the UNSC forces were wiped out, though the cost to the Covenant was far greater as their capital station High Charity was completely assimilated by the Flood. Though the Covenant managed to activate the Halo, a joint UNSC-Covenant Separatist group were able to cease firing before it completed its preparation sequence, thus activating an emergency situation across the entire Array and making them aware of the existence of the Ark.

While the remains of the Covenant Loyalists travelled to Earth using their recently-acquired knowledge of the portal to the Ark, where all the Halos could be fired at once, the Flood sent a ship in pursuit, though the infection was contained. The UNSC and Covenant Separatists followed the Loyalists through the Portal to the Ark, initiating a final battle that ended the Human-Covenant War. However, the Flood, having finally located the Ark, deposited High Charity to its location and initiated a massive wave of infection across the Ark. The Master Chief initiated a plan to damage the Ark and destroy the Flood once and for all by prematurely activating the newly constructed Installation-04B, and though few survivors made it out of the ensuing engagement, the plan succeeded and the Flood were erradicated once more. Sometime after, the constructs on the Ark began restoration efforts to repair the damages incurred during the battle.

The Requiem Campaign[]

Following the battle of the Ark, the Master Chief was found by a Covenant Remnant pirate faction lead by Jul 'Mdama, who had come to worship the singular Didact entity as a God and had been attempting entry into his Requiem Shield World. The arrival of the Master Chief opened the gateway; the Ur-Didact, upon detecting their presence, manipulated signals of the approaching rescue ship, the UNSC Infinity, to get the Master Chief to release him from his imprisonment.

Succeeding, the Ur-Didact regained control of his Promethean army and made preparations to depart from Requiem and claim his vengeance on Mankind. The Master Chief learned through a leftover message from the Librarian of the Ur-Didact's hatred, the original fate of Ancient Humanity, and the Ur-Didact's objective to reclaim the Composer and use it on Humanity. Though the Master Chief attempted to stop him, the limitations imposed on him by the Infinity's Captain Andrew Del Rio prevented his success and the Ur-Didact recovered his warship, the Mantle's Approach, and escaped Requiem with his Covenant Remnant followers. Arriving at Installation 03, the Ur-Didact located the Composer, which was hidden away in a UNSC research station, and tested its functionality by activating it on the station's occupants to replenish his Promethean reserves. Following the successful harvesting, the Didact departed for Earth, though was closely pursued by the Master Chief. Although the Ur-Didact could not be stopped by the UNSC defense force at Earth and succeeded in firing the Composer on Earth, the Master Chief defeated the Forerunner in personal combat and detonated a nuke within the ship, destroying it and the Composer. Though the entirety of New Phoenix's population were harvested, the rest of Earth was saved.



Variations of Forerunners based on Rate

The Forerunners resembled Humanoid species in basic silhouette, a bipedal species with one head and torso, two arms and two legs, two eyes and a mouth. However, the Forerunners differred in other physical traits, being larger in stature and more physically developed, being stronger and faster as well as more resilient to damage and disease. Depending on the Rate and Mutation level, Forerunners could be anywhere between just over 2 meters in height to over 4 meters tall.

Additionally, Forerunners possessed eyes with black sclerae as opposed to Humans' white, lacked protruding noses and instead having nostril slits in the place of a nose, and lacking ears while instead sporting bulbous protrusions on the sides of their head. At least in some cases, their feet lacked toes but instead resembled the structure of Sangheili feet with two toe-like protrusions on each foot. Additionally, while the number of fingers varied based on Rate and level of Mutation, most Forerunners had six fingers, two of them being opposable thumbs. The skin tone of Forerunners varied almost as much as Humans, though including other shades. Forerunner skin colors were composed of gray, black, blue, pink, tan, or a mixture thereof.

Forerunners were sexually dimorphic mirroring that of Humans and other similar species, having a male and female gender. Females were more slender and smaller in stature than males, who exibited increased muscularity and more powerful bodies. Forerunners had a bioligical need to sleep like most other life-forms, though typically this necessity was eliminated by the use of personal armor.

The Forerunners had a genetic code that was remarkably similar to humans, though they were not known to be genetically related.


Forerunners possessed highly advanced mental capabilities, far beyond those of a Human in the case of their higher forms. Though typically augmented further with the use of personal armor, Forerunners without the aid of artificial enhancement were still superior to Humans and other sapient species in regards to sheer intelligence and memory storage capacity. This enabled Forerunners to be able to remember enormous amounts of precise information, such as reciting a verbal control code consisting of hundreds of completely random words and numbers after thousands of years. Warriors, as another example, were biologically conditioned by their Mutations to be able to process several events simultaneously even without their armor.


Over the course of their lives, Forerunners underwent a number of artificially induced mutations, modifying their bodies to better suit the field of work of their Rate. More specific aspects of their appearance varied with lineage, age and even personal tastes. Before their first mutation, as Manipulars, Forerunners were tall and slender, and possessed patches of fine, purple-pink or white fur on the top of their heads, along their nape and shoulder area, as well as the backs of their hands. Their facial features were closer in similarity to Humans, and they were capable of making analogous expressions, but this changed as they mutated to their higher forms, which characteristically had stiffer facial muscles and a more limited ability to convey emotions.

When a Manipular was ready to work within a particular Rate, they would undergo an artificially-induced transformation into a more advanced form, which differed depending on the Manipular's chosen caste. The transition typically occurred over a long period of time. A typical Forerunner would undergo several Mutations over the course of a lifetime, though this was not always the case. Mutations altered Forerunners' abilities and physical shape to suit their class; Warriors, for example, underwent Mutations that made them stronger and more robust. After their first Mutation, Forerunners also gained the ability to access the Domain, a realm of information where the entire collated knowledge of the Forerunner civilization was contained.

In emergency circumstances, an operation known as a "Brevet Mutation" could be performed on a Manipular. This was a Mutation that occurred over a much briefer period of time, and was often painful. Typically, these were only performed in dire circumstances or situations outside of normal boundaries, and unlike standard Mutations could involve a Manipular slated for one Rate to transition into that of another Rate. Rarely, a Brevet Mutation could fail and result in deformities; there were rumors that Forerunners whose Mutations had failed were sequestered in special enclaves, hidden from the general population.


A Council hearing on the Capital

The Forerunners were lead by the Ecumene Council, based in the Capital Maethrillian and composed of 500 Councilors from various rates and a huge network of supporting Ancillas known as the Council Metarchy. The head of the Council was known as the First Councilor. The Forerunner civilization was based around the Mantle of Responsibility, an ideology of assuming the role to protect all life touched by the Precursors in the Galaxy. It was believed that the Forerunners gained the Mantle as a birthright from the Precursors after they vanished.

As a result of their perceived status as universal guardians, the Forerunners largely secluded themselves above other species. They monitored the evolution of other sentient species throughout the galaxy, intervening in ways that ensured their civilizations would follow paths of peace, free of conflict, but also so that they would not challenge Forerunner dominance. To maintain their position, the Forerunners committed acts such as relocating other species from their homeworlds in order to expand their own empire or gain control of new resources. They also enforced the Mantle by hindering the development of other species, even reducing opposing species to small populations of specimens, as they did with early Humanity. Those species who submitted to Forerunner rule lived within the ecumene as subject species, allied with but ultimately subservient to the Forerunners; some of these species helped eliminate pockets of human resistance after the Human-Forerunner wars.

The Forerunners themselves were a race almost entirely without conflict; although political disputes were not uncommon, violence or war between Forerunners was almost unheard of, the last Forerunner civil wars having been fought half a million years before their civilization's end. As such, the Warriors, who conducted most of the Forerunners' military operations, were often looked down upon by the higher rates, as their actions were perceived to be contradictory to the Forerunners' role of preserving life. While they generally strove for peace, when provoked to a war, the Warriors would carry out the war ruthlessly and thoroughly, as they believed defiance of their rule was equal to showing contempt to the Mantle itself.

Destiny and Fate[]

Based upon the Mantle, the Forerunners followed a philosophical belief in a concept referred to as "Living Time." This assumed that the universe was a living entity enriched by the collective experience of ever-changing life. According to the premise of Living Time, struggle, competition and even war were not at odds with the harmony of the cosmos, as they were regarded as a natural part of life. However, excessive and needless cruelty and destruction were seen as introducing an imbalance to the harmony of Living Time. The Forerunners believed that individual lives would eventually be summoned and judged at the End of Living Time.

Naming Conventions[]

Forerunner names had concrete meanings in their language, and commonly consisted of a combination of words expressing positive attributes in a grandiose, somewhat poetic manner. In many cases, a Forerunner's name was associated with typical terminology involved with the practices of the rate they were born into; for example, "Bornstellar-Makes-Eternal-Lasting" reflects his Builder lineage. In informal conversation, these names were typically shortened, with only a single part being used.


Forerunner customs involving marriage were complex. Lower Rates married often out of affection and love, while higher Rates typically did so for political reasons such as establishing connections to bring separate familial relations close together. While generally not practiced, intermarriage between rates was not unheard of. Additionally, a certain degree of courtship between rates was considered commonplace before individuals were espoused to formal marriage. Polygamy was also an accepted practice, at least among the higher Rates with some individual males having many wives. At certain points in their lives, females would enter a "millennial interim", a period when they would not bear children. It was highly frowned upon to attempt to mate with a female during this time.

Death and Suicide[]

When a Forerunner died, elaborate ceremonies would be enacted before their remains were disposed of. First, the Forerunner's last memories would be extracted from their armor, which preserved a few hours of the occupant's mental patterns. This reduced splinter of personality would be placed in a Time-Locked Durance with a half-life of more than a million years. The body would then be fusion-torched in a solemn ceremony attended only by close relations. A bit of plasma from the immolation was preserved by the appointed Master of the Mantle, who secured it along with the essence in the Durance. The Durance was then given to the closest members of the dead Forerunner's family, who were charged with making sure that it would never be abused. Families and rates were very protective of such places, and tampering with a family Durance was considered sacrilege.

Though sometimes considered noble for a just cause such as ensuring victory in a desperate battle, the taking of one's own life was strictly forbidden among Forerunners. There was also a cultural stigma associated with expressing emotions; while even certain higher forms were capable of producing some semblance of a smile or laughter, for example, such uncontrolled display of emotions was regarded as barbaric.


Forerunner culture remained highly unchanged throughout their existence, with fundamental aspects of their society including the Mantle and their Rate-based hierarchy going unmodified for millions of years. Having a rigid social structure, the Forerunners were a people where one's position would be determined by Rate, typically inheritance of their family's Rate. Cultural practices and customs varied by rate and position; generally, Forerunner culture was full of formality and ritual, particularly with the Builders, the highest of the rates. Forerunners placed a great deal of value on family lineage and tradition, and one's rate and social standing were largely hereditary. Should a Forerunner desire to follow a path outside of their Rate, their families would often look down upon them as outcasts if they managed to succeed in the endeavor.


The Forerunners were divided in a number of important Castes which determined their fields of service to their society. Below are the main Rates.


The Builders were responsible for the design and construction of most Forerunner technology and architecture, including weapons, ships, and megastructures. Standing at the height of Forerunner Society, the Builders enjoyed a comfortable lifestyle of wealth and measure of political control over the Forerunners. The Master Builder is the title given to the leader of the Builder Caste.


Also known as Warrior-Servants, the Warriors were the primary military force of the Forerunners and were charged with the defense and protection of the Ecumene, participating in wars as the soldiers of the Forerunners. The Prometheans were the most elite of the Warriors, and their direct commander, the Protector of the Ecumene, is the leader of the Warrior Caste.


The Lifeworkers assumed the role of overseeing biology and medicine, and were the main healers of the Forerunner society as well as performing experimentations on various forms of life. The leader of the Lifeworker Caste was known as the Lifeshaper.


The Miners were responsible for obtaining raw materials and resources required for the work of the Builders, as well as stellar and planetary engineering. Miner stellar engineers were known as Plasma Jockeys.


The Juridicals were the rate charged with judicial matters, including the investigation of crimes and the judgment of criminals within Forerunner society. The Juridical rate was home to Catalog, a collective of evidence-gathering agents. The head of the Juridical rate was known as the Master Juridical.


The Halo Array

The Forerunners currently remain as one of the most technologically advanced races ever known in the Milky Way Galaxy. Much of the development of sentient life throughout the Galaxy was due to the manipulations of the Forerunners. Though the Forerunners themselves are gone, their leftover technology has been found and catalogued by a large number of sapient races throughout space, leading to the advancement of said races in their capabilities of interstellar travel and weapons, among other applications.


Forerunner building structures and starships make heavy use of geometric angles. For example, buildings are usually trapezoidal while starships are triangular, though exceptions do exist.

Most Forerunner architecture is constructed with a special type of silver-gray metal that resists deterioration, bullets, plasma bolts and fire, as made evident by Forerunner structures standing in pristine condition 100,000 - 150,000 years after they were built. However, their resistance to heavy plasma fire is limited; concentrated plasma discharge is capable of destroying some Forerunner architecture. Other structures and high-tier starships were built with a superior golden-bronze colored metal.

The Forerunners were also highly skilled at creating stone architecture. Typically, these buildings were built from a pale brown or tan stone. These structures were more subject to wear and aging, but their architectural sophistication remains apparent after 100,000 years. In some structures, patterns and symbols had been embedded in the rock itself by manipulating its mineral inclusions. Most interestingly, certain Forerunner buildings incorporated "mutable" stonework: a stone Forerunner structure in Ontom, Sangheilios featured passages that could shift and change by literally reshaping the stone from which their walls were built.

In addition to physical structures, a large portion of Forerunner architecture is actually composed of sophisticated solidified photons, dubbed Hard-Light construction. Such architecture is often crafted in the likeness of corporeal matter. Hard Light structures can form complex shapes and sizes depending on the capabilities of its generators. This technology has many uses, from acting as basic structural components such as platforms or walls to decorating and furnishing everything from Forerunner homes and public spaces to starship interiors. Hard Light structures are capable of materializing when needed and then melting away when deactivated. Immensely large structures, such as massive command warships, employ Hard Light bonding as a means of maintaining structural integrity. The immaterial and flexible nature of this technology lends it a great deal of uses, but as a drawback, it is susceptible to power failures.

Personal Armor[]

Forerunner Warriors wearing Combat Skins

The Forerunners relied heavily on Personal Amor which, in addition to protecting the wearer from harm, augmented their physiology and mental faculties. Among many other advantages, it made their lifespans virtually indefinite by providing constant life support and medical care. Forerunner Armor provided advanced energy shielding and informational access, and were specialized to assist its wearer in performing the tasks of their Rate. For example, Warrior Armor, known as Combat Skins, would protect its wearer in combat and offer offensive capabilities, while Lifeworker Armor provided medical aid and biological research capabilities.

Thanks to their advanced life-support and medical technology, Forerunners could maintain a youthful appearance for thousands of years should they so choose. Forerunner armor was generally capable of healing most injuries which would otherwise be certainly lethal, including fatal doses of radiation. A Forerunner's base physical abilities were further augmented by their use of personal armor, which integrated with the wearer neurally and stored sensory information and memories, even consistently backing up the wearer's consciousness. The armor also allowed Forerunners direct information transfer to one another, which could also be employed in the form of "silent conversation". Higher-form Forerunners had the ability to process enormous amounts of information simultaneously; for example, Warrior-Servant commanders could simultaneously process the sensory input of thousands of their subordinates while coordinating large-scale battles and themselves experiencing reality in multiple separate frames of reference with variable streams of time. The use of an ancilla enabled Forerunners to recall any past event with exact accuracy.


Example of a handheld Forerunner weapon

The weapons of the Forerunners varied broadly in form and capacity, though are far more advanced than current weaponry. The Forerunners typically made use of directed energy weapons as well as electronic warfare and offensive technologies based on energy fields. The typical infantry weapon issued to soldiers used solidified photons known as "Hard Light," though other weapons included particle beams, antimatter, or super-heated plasma. Though many weapons fill basic roles and have clear analogues to Human-type weapons, many Forerunner weapons were exotic and possessed unique qualities. Many weapons were operated by automotons, the most recognizable being the Sentinel while another common automated user of weapons included the Armiger constructs, though the most feared were the Promethean constructs. Automated emplacements were also used in defensive roles to safeguard sites in hostile zones. Some energy weapons are designed to function in combination with other similar weapons, augmenting each other's effects into a larger effect for increased performance.

During the Forerunner-Flood War, many weapons of the Forerunners were incorporated with an efect to disintegrate their targets upon inflicting a critical hit, preventing the Flood from reanimating the corpse and make use of their biological matter. Other conventional weapons proved effective in simply burning Flood forms to the point they could not be revived by Infection Forms. Many Forerunner firearms, like the rest of their technology, are composed of disparate parts held together by energy fields and display self-assembling capabilities.

When participating in a battle, the Forerunners made heavy use of mechanized weapon platforms to carry out most of the work, though when participating directly, Forerunner Warriors used advanced personal armor known as Combat Skins that offered incredible protection from outside trauma, as well as larger exoskeletons of greater size and destructive capacities capable of travelling across a planet and devastating a whole city alone. Individuals or assets with a designation of high status were equipped with more powerful weaponry. Installation Monitors, for example, generally relied upon the protection of Sentinels, but were capable of defending themselves when necessary.

Forerunner Weapons were not limited to operation within normal space. The Halos and the Line Installations, for example, were both specifically geared to also function within slipspace, thus even affecting targets transitioning through slipspace when most other weapons cannot affect a vessel as it is in transit.

On a large scale, Forerunner weapons were manufactured out of various forms of exotic matter on an atomic level in hyper-precise nanofabrication forges in accordance with instructions programmed into design seeds by Forerunner pattern-weavers working in conjunction with an ancilla. Because of the fidelity of these manufacturing methods, every weapon and piece of technology could be built perfectly identical down to the atomic level. While these weapons were highly uniform, many Warriors preferred to craft their own weapons and armor to be unique and aesthetically pleasing whenever possible.


The Forerunner Dreadnought

Forerunner spacecraft remain the most advanced in faster than light travel specifically using slipspace. Using special crystals embedded in their drives, Forerunner ships also utilized reaction drives which harnessed virtual particles as a propulsive force; however, they still required the use of onboard reaction mass. In addition, the Forerunners created a network of slipspace portals for high-traffic slipspace transit across the galaxy. Aboard starships, limited inertial dampening was achieved through the use of buffer fields, but during extreme acceleration, the occupants' armors had to be locked to the deck.

Forerunner warships could be enormous in scale; the Ur-Didact's personal command vessel, Mantle's Approach, was 341 kilometers in height and was even then surpassed in size by the largest Forerunner ships.

The interiors of all Forerunner ships were not entirely composed of matter, typically allowing the captain to configure the ship's internal layout and decoration at will. At least some types of Forerunner craft can alter their geometry to better suit their current situation; for example, making the ship more aerodynamic in preparation for surface landing.


The Forerunner's understanding and access to slipspace was far superior to that of any other race even to this day. While alternative methods of faster than light travel exist including the use of other dimensional transits similar to slipspace, Forerunner technology remains the most advanced specifically for slipspace. The Forerunners were able to store large areas of space within slipspace, permitting them to create Dyson-Sphere structures such as Onyx; additionally, they crafted weapons specifically designed to target enemies in slipspace whether in normal or slipspace; and also had advanced applications of slipspace transit, permitting them to teleport instantly through slipspace in shorter ranges while facilitating the passage of large masses or incredible numbers of structures through huge distances across slipspace in short time.


While the Forerunners' architectural and technological prowess is legendary, their masterpieces also extended to the fields of stellar and planetary engineering. They were capable of manipulating the lifespans of stars, stabilizing young stars to last for longer periods of time or harnessing dozens of stars for immense energy production. Forerunner Miners even experimented with suspending the stellar collapse of a star, though this was rarely performed due to the incredible amounts of energy required to maintain it.

Forerunners could also manipulate planetary formations, collapsing asteroid fields in molten masses before cooling it down and forming terrestrial planets in less than ten thousand years. A similar process existed for gas giants.


Installation 05

The most famous of the recognizable Forerunner constructions is the Halo Array, a series of massive ringworlds primarily designed to wipe out life on a galactic scale but also serving a number of other purposes, including housing civilizations and life upon their surfaces. The Halos were officially referred to as Installations with a numerical designation following; they were secondarily known as Fortress Worlds, or the Swords of the Forerunners.

Shield Worlds[]

Shield World 0459

The other recognizable Forerunner construction is the vast amount of artificial planets known as Shield Worlds. Known as the Shields of the Forerunners, these artificial planets varied in design and size, though all were employed as a defensive measure from external attack by a hostile force by housing its inhabitants within the center of the planet itself. The typical design followed the first Shield World Requiem, which was a hollowed sphere with an interior planetoid body on the inside; other designs however, included the Etran Harborage Shield World where a hollow sphere contained its interior surface inside the surface of the sphere while surrounding a central star, and the rare Onyx design used a Dyson sphere design compressed within slipspace to contain a sizeable area of space around a star within a tiny area of normal space within a planet made up of trillions of advanced Sentinel constructs.


Other megastructures were known to exist throughout the Forerunner Empire. The largest space-based megastructure made by the Forerunners is the Capital Maethrillian, the center of their Empire.