- "We are Forerunners, guardians of all that exists. The roots of the galaxy have grown deep under our careful tending. Where there is life, the wisdom of our countless generations has saturated the soil. Our strength is a luminous sun towards which all intelligence blossoms and the impervious shelter beneath which it has prospered."
- -The Ur-Didact
The Forerunners were a highly advanced and ancient species whose empire, the Ecumene, was spread across three million fertile worlds in the Milky Way galaxy approximately 100,000 years ago. The Forerunners were the creators and builders of many magnificent installations such the Halo Array, the Ark, the Greater Ark, the Shield Worlds, as well as numerous artifacts that were found on the planets Reach, Earth, Sigma Octanus IV, Harvest, Arcadia, Sanghelios, Kholo and the Prophets Homeworld.
The Forerunners took upon themselves the role of caretakers of the galaxy, and believed that this "Mantle" had been passed down to them by the Precursors, an even more powerful race that preceded the Forerunner civilization. Before their disappearance from the galaxy, the Forerunners would name humanity their successors, identifying them with the title "Reclaimer".
The alien alliance known as the Covenant worshiped the Forerunners as gods, deriving much of their technology from Forerunner artifacts found throughout the galaxy, and believing any who defaced these relics to be Heretics.
The Forerunners were a very advanced civilization with their ecumene inhabiting three million worlds and controlling many more at their peak. Forerunners originated on the planet Ghibalb in the Orion complex. After gaining a small interstellar empire, the Forerunners began attempting to manipulate several stars in the region, resulting in a series of supernovae destroying Ghibalb and a large portion of their fledgling interstellar empire. As their empire expanded, they expected the Precursors to pass the Mantle of Responsibility down to them, and were outraged when the Precursors decided to pass the mantle down to prehistoric humans instead. After this, the Forerunners violently and swiftly attacked and destroyed the Precursors that inhabited the Milky Way. The Precursors refused to defend themselves against their own creations, and let the Forerunners exterminate them, as the Forerunners could only destroy their physical forms, not their immaterial consciousness. Eventually the Forerunners wiped out most of the Milky Ways Precursors. The Forerunners reached their peak before activating the Halo Array around 100,000 years ago, exactly as planned.
Being one of the only two known races (the other being prehistoric Humanity) ever to achieve Tier 1 technology based on the Technological Achievement Tiers measurement, they were only superseded by the mysterious Precursors at Tier 0; evidence of which has been found throughout the milky way and even in the Large Magellanic Cloud on one forerunner expedition. The fact that the Halos were scattered around the galaxy also hints at the possibility that the Forerunner Empire covered most, if not all, of the galaxy. They were even candidates to inherit the Mantle to protect all life in the galaxy, believing it was their role to protect due to them being so advanced. At some point in their history, the Forerunners and prehistoric Humanity entered a war with each other. The Forerunners believed the Humans
were aggressively expanding their empire, but the truth was that the Humans encountered an extra-galactic parasite known as The Flood, and were running from it. Humanity tried to explain the truth to the Forerunners, but by the time they went to look for the truth, the Humans had already pushed the Flood back. Unable to fight a war on 2 fronts, prehistoric Humanity lost the war. To punish them, the Forerunners devolved them into primitives and sealed them on their homeworld, Erde-Tyrene (Earth). Later in their history, a Forerunner survey team came into contact with The Flood themselves on the planet G 617 g, finally proving Humanity's story (details of this first contact are unavailable). After this first contact, the Forerunners realized the great danger that The Flood posed to the entire galaxy and attempted to contain them. The attempt to contain The Flood was a failure, primarily because in the beginning, they treated The Flood as a disease, attempting to contain it and quarantine it, instead of treating it as a severe threat and declaring an all out war on The Flood. They did not start war until it was far too late.
When the Forerunners were unable to contain The Flood outbreak, war between the two factions broke loose. During the 300 years of conflict, the Forerunner studied The Flood in labs such as the gas mine located in the atmosphere of Threshold, looking for some sort of weakness. Eventually they created the Halo Array, a weapon of last resort designed to starve The Flood to death by killing all sentient life with enough biomass to sustain them. It should be noted, though, that the Forerunners Halo Arrays also killed non sentient life, like animals.
At first, the Forerunners were reluctant to use the Array, believing that they should continue to embrace the Mantle and to protect life, not destroy it. The Gravemind managed to convince a Contender-class AI, Mendicant Bias, to unite with The Flood. The Ecumene soon grew so desperate that they caused "premature stellar collapse", or destroying suns to causes supernovae that destroyed entire star systems. Mendicant Bias soon led his massive fleet in an attack on the "Maginot Line", the final barrier between the Forerunner inner worlds and the outer. The Forerunners were given no choice but to activate the Halo rings, indexing most intelligent lifeforms such as Humans, Sangheili and so on, killing themselves and all life of sufficient biomass and cognitive ability in the Milky Way, with the exception of those species safely placed on the Ark.
After the Array was fired and the remaining Flood had been eliminated, the remaining Forerunners spearheaded the reseeding of the galaxy, thereby returning all indexed lifeforms to their homeworlds. Once this was completed, the surviving Forerunners disappeared for unknown reasons. They most likely left the Galaxy.
Forerunner technology was highly cultivated and progressive. They managed to create solidified surfaces out of meticulous energy, or "Hard Light", construct a Halo-wide teleportation grid, creating warships over 350km long, and create and utilize a number of other advanced machinery. The Halo Rings themselves, the Micro-Dyson Mark II sphere, which is connected through a portal to the shield world Onyx, and the Ark (Installation 00) are, above all others, the most significant pieces of Forerunner technology. The planet Onyx in particular demonstrates both their ability for engineering on a grand scale, and their near transcendent grasp of Slipspace technology.
Covenant Luminaries (which are actually stolen Forerunner equipment designed to detect other Forerunner objects) can detect Humans, previously mislabeled as "Forerunner Artifacts", leading to the initial Human-Covenant contact which sparked a seemingly endless war. The idea of living Forerunners in the Galaxy (described by the Oracle as Reclaimers) terrified the Covenant leadership. In an attempt to protect their religion the Prophets of Truth, Regret and Mercy concealed the true identity of Humanity to the rest of the Covenant and deemed them as heretics, thus sparking the Human-Covenant War.
Forerunners have the technology to reproduce entire individuals from encoded DNA/RNA/silicon samples in data streams. This was mentioned in the Bestiarum: "DNA/RNA/Silicon samples are encoded in this data stream. Reproduction of individuals for analysis is prohibited by this facility."
The Forerunners appeared to be genetically similar to Humans, resembling them greatly.
Armory and Weaponry
Forerunner constructs and sentries use a broad variety of incredibly advanced and powerful weapons, typically firing Hard Light based projectiles. These weapons proved to be very effective when battling the Flood, burning Flood forms to the point that their Bio Mass is completely destroyed. The Forerunners have also proven to be able to merge plasma beams together into one stream to amplify its power. The Forerunners installed and constructed these intricate beam weapons inside their paradigm Arrays, allowing them to build an army of machines to battle The Flood without sending any Forerunner to the front lines. Forerunners evidently made active use of plasma weaponry as well; the Covenant's own weapons and technology are solely based on Forerunner artifacts.
The Sentinels wield orange-colored directed energy beams, used primarily for fighting the Flood. Sentinel Majors however, have a more powerful and accurate version of the beam, which sports superior energy output, at the cost of overheating issues. These more advanced energy beams are colored blue. All variants of these Sentinel Beams can be wielded by Humans and certain Covenant races.
Meanwhile, Enforcers are equipped with multiple packs of small grenades, or mortar-like explosives launched over the top of their shield. The Enforcer also boasts a pair of Pulse Beams, which fire clusters of smaller red Needler-like projectiles or bolts of energy at an incredibly high rate of fire. These pulse beams are primarily used against infantry at close range. These mammoth constructs also seem capable of lifting even tanks, using some sort of magnetic or anti-gravity grapple, before crushing the target between their massive 'arms'. The Constructors' repair beam can also be considered a weapon, but with minimal damage output.
The Forerunners also constructed Automated Turrets that fire blue beams similar to those of sentinel majors. These turrets themselves resemble stripped-down sentinels, and hover in mid-air, tracking enemy targets, but are otherwise immobile.
The Monitors had the ability to defend themselves against the Flood using a focused beam similar to the Sentinel's beam, but much more powerful.
The Forerunners themselves used extremely advanced exoskeletons called Combat Skins. The classification system for Combat Skins ranges from a Class 1 Combat Skin to Class 18 and above Combat Skin. The human MJOLNIR Mark V Armor, an extremely powerful Exoskeleton and one of the most advanced suit of armour in the modern times, is roughly on par with a Class 2 Combat Skin.
Art and Architecture
Forerunner architecture is noted mainly for being large-scale and geometric in style, with a triangular theme being the most commonly observed design. The Forerunners had a habit of creating natural habitats, such as those of the Halo rings, which tend to be very elaborate, with numerous extrapolations of the basic design of a construct appearing to be purely decorative. In addition, the structures were engineered to compliment the natural landscape, as opposed to the modern idea of replacing it. That said, their distinctive beauty are not restricted to Halo Array network. The Aztec-esque stones of Côte D'Azur, the arches and weathered inscriptions of Sigma Octanus IV, the intricate caverns and three-kilometer holographic dome beneath ONI's Reach complex, the ancient stepping-stones of Balaho, and the Forerunner City discovered in the depths of the human-inhabited Onyx, all display the Forerunner's innovative architectures. Most Forerunner architecture is constructed with a special type of metal that resists deterioration, bullets, plasma bolts and fire, as made evident by Forerunner structures standing in pristine condition 100,000-150,500 years after they were built. However their resistance to plasma fire is limited; in Halo: Ghosts of Onyx the Elites blasted a hole in a Forerunner wall with plasma weapons. In Halo 2, Sgt. Avery Johnson destroyed the door to the control room of Delta Halo with a Scarab. Other structures are constructed out of traditional materials, such as chalcedonic quartz, which does not preserve nearly so well. These structures employ complex geometric shapes that appear to operate in dimensions higher than human understanding can comprehend. The Forerunners also decorated the interiors of their structures with a complex web of engraved straight lines and applied decorative touches and designs to nearly everything that they built, from structures to weapons. Even the Sentinel robotic drones possess small holographic Forerunner script around their "eyes".
Forerunner architecture distinguishes itself from Covenant structures in that they incorporate the use of angles, usually at either extremely sharp degrees (as the Forerunner buildings are usually triangular), or at forty-five degree angles, most notably seen in Halo: Combat Evolved. Originally, the ideas and concepts on Forerunner structures and technology was that it would be sleek and curved to give it an advanced feel. However, Bungie wanted the structures to feel as if they could stand the test of time and redesigned them to be solid and monolithic. The smooth, near-organic design would later be adopted by the Covenant in their architecture, although they did not adopt the Forerunner tradition of decorating their structures with glyphs. In Halo Wars the Forerunner counting system is used to open and close portals on the last level.
While the Forerunners' architectural and technological prowess is legendary among the Covenant and UNSC, their masterpieces also extended to the fields of stellar engineering. At least three Forerunner sites, the Shield World Onyx, the Ark, and the Micro Dyson Sphere that holds the Apex, made use of suns where none should exist. The Shield World existed permanently in Slipspace, where solar systems outside of a Dyson Sphere cannot exist, and the Ark was located far outside of the galaxy where galactic material would have been insufficient to form the sun that illuminates the Ark. The sun at the center of the Dyson Sphere where the Apex was housed was abnormally small, in order to accommodate the planet-sized Dyson Sphere. Whether these suns are artificially engineered or simply moved from another star system by the Forerunner is unknown: either would have been an enormous technological achievement. Another known Shield World is the planet discovered by the Spirit of Fire. This world had an outer crust like Onyx, but its inner Dyson sphere was accessed through a long narrow tunnel hidden under one of the planet's oceans. Once through the tunnel, the Spirit of Fire had to pass through several "cleansing rings" in order to make it to the center of the planet. This Dyson sphere, unlike the Onyx Dyson sphere, was not separated in slipspace but was actually constructed on what appeared to be hollowed out inside of the planet. This sphere seemed to have had an artificially created sun like the one on the Ark.
The Ark is confirmed to be artificial, due to its unnatural "flower head" shape. It is likewise unknown if these are the only stellar engineering achievements the Forerunners made. However, it is clear that manipulation of slipspace allowed the Forerunners to transport and position these structures throughout the galaxy.
Glyphs and Symbols
The Forerunner glyphs seem to be based on a series of circular, complex shapes. The glyphs have been inscribed almost everywhere Forerunners were once present, from different areas of Earth, to the Halos. They were also known to put these glyphs and symbols onto their weapons, machinery and clothing, something the Covenant also copied, evident with the Forerunner symbols placed on the hilt of the Energy Sword.
Forerunner in Covenant Religions
The Covenant venerate the Forerunners as gods and referred to them as the Ancients, believing that the Halo Array elevated the Forerunner to godhood instead of killing them. As such, they have appropriated many Forerunner technologies and artifacts, and such searching led to the Covenant coming to Harvest in the first place, therefore beginning the Human-Covenant War. Also they dedicated a significant amount of time to the search for other "holy relics" such as the Halo Installations, believing that they can follow the Forerunners into godhood. This is referred to as the "Great Journey" by the Covenant races. The Covenant believe that the Forerunner's ascension to godhood was finalized after the rings were fired.