Massive, eurypterid-like head, four arms, barbed tail extending from head.
15 meters tall, 13 meters wide.
- "We meet again, young one. I am the last of those who gave you breath and shape and form, millions of years ago. I am the last of those your kind rose up against and ruthlessly destroyed. I am the last Precursor. And our answer is at hand."
- —The Primordial speaking to the Didact.
The Primordial, also called the Captive or the Timeless One, and the Beast by the Tudejsa, was a mysterious being of great power once detained on Charum Hakkor. Its precise nature remains unclear, but it appears to have been both the last surviving Precursor, and a Gravemind, a physical embodiment of the Flood's collective consciousness.
The exact origins of the Primordial remain a mystery. It is known that following their defeat at the hands of the Forerunners circa 10,000,000 BCE, many of the remaining Precursors transmuted themselves into organic particles that would re-constitute their original forms at a later time. Over the millions of years that followed the Precursors' fall, this powder degraded and became defective; instead of re-forming the Precursors' original bodies, it instead resulted in misshapen life-forms that ravenously assimilated biomatter they came in contact with - the earliest stages of the Flood parasite.
Not all Precursors chose this fate; a number went into deep stasis without reducing themselves to dust. The Primordial, however, was evidently not a Precursor as they appeared in their original forms. Instead, it appears to have been an artificial being, perhaps a very early form of Gravemind, created from several creatures; the exact number was never determined, but Forthencho theorized that there had been at least twelve. At the same time, Forerunner researchers were unable to conclusively determine whether the entity was truly connected to the Flood, suggesting that it may have represented a considerably different, more primitive form of what would eventually become the Flood. Whatever its actual nature or origin, the Primordial's consciousness was synonymous with that of the later Gravemind.
The Primordial was placed in dormancy within an asteroid outside the margins of the galaxy around 9,000,000 BCE; a million years after the Forerunners wiped out the Precursors. According to the Gravemind, the Primordial "arrived" in this location at this time; who was responsible for placing the being in stasis is unclear, though it is most likely to have been early Forerunners.
Several decades before the end of the Human-Forerunner War, circa 109,090 BCE, the creature was discovered by prehistoric humans on a small planetoid near the edge of the galaxy, hibernating inside a stasis capsule of Precursor origin. Yprin Yprikushma then transported it to a vast arena on Charum Hakkor, where human researchers found a way to revive the creature. At a later date, the captive's prison was sealed with a timelock as a further precautionary measure.
Despite the advanced nature of Precursor technology, Yprikushma and her research team managed to find a way to communicate with the captive for brief periods of time. They came to regard the creature within the cell as an oracle of sorts, asking it questions in the hopes of gaining greater understanding. Most of the time, the prisoner's answers were confused or unintelligible. When asked about the Flood, the answers given to the humans present were so deeply horrified that many of them committed suicide. 
Following the end of the Human-Forerunner War, the Didact and a group of Prometheans gained access to the prisoner, though only the Didact ultimately faced it in person. Initially, the Didact believed the Primordial to be a hoax - a psychological weapon created by the humans to demoralize the Forerunners. It was also theorized that the captive may have been preserved as an ultimate weapon of last resort, to be unleashed in case of an imminent defeat of the humans and the San 'Shyuum. However, upon conversing with the creature, the Didact discovered that it was - or claimed to be - the last Precursor, and that the Forerunners had rebelled against the Precursors. The Didact revealed this information to no one, regarding its potential implications as being too destructive.
 Installation 07
When the Contender-class artificial intelligence Mendicant Bias tested Installation 07, one of the original twelve Halo rings, in the Charum Hakkor system, the Halo's energies destroyed every Precursor structure on the planet, freeing the prisoner. The creature was then taken to Mendicant Bias' Halo for study; both the Halo and Mendicant Bias disappeared soon after, not to return for 43 years.
Lifeworkers in the employ of Master Builder Faber initially studied the Primordial for some time, but their research as to its nature proved inconclusive; while some believed it was connected to the Flood, others dismissed this theory. The Master Builder soon withdrew the Lifeworker researchers and assigned Mendicant Bias to interrogate the creature. The AI conversed with the Primordial, who in turn explained the nature of the Flood, the Mantle, and the eons-long plan of the Precursors. Mendicant Bias was eventually persuaded by the Primordial's arguments, and deliberately succumbed to what the Forerunners referred to as the "logic plague", a state comparable to rampancy. The AI then defected to the Flood, and referred to the Primordial as its master, demonstrating its denial of the Forerunners.
Having swayed Mendicant Bias to its cause, the Primordial began to oversee and redirect activities on Installation 07. Through the use of Lifeworker beacons located across the Halo, it and Mendicant Bias broadcast signals that affected the geas of the ring's transplanted human population, causing them to migrate en masse to Flood research facilities on the installation. During this time, it used a large levitating platform to travel around the ring.
- "It is your task to kill this servant. That another may be freed."
- —The Primordial speaking to the Didact.
After reclaiming Installation 07, the IsoDidact imprisoned the Primordial within a reverse-stasis chamber, and alongside the wounded Chakas, interrogated the entity. During the course of their conversation, they came to realize that the Primordial was not what they initially thought it was. Even as it was being broken down by the reversed stasis chamber, the Primordial claimed that the Flood and the Precursors were synonymous, though despite the Didact's queries, it did not disclose the precise nature of their relationship. The Primordial provided further clarification on the subject of the Mantle, the purpose of the Flood, and the role of the humans in its ancient plan: the Forerunners were never meant to inherit the Mantle, and that humanity would succeed them in order to be tested for inheriting the Mantle.
It also implied that there is no true cure for the Flood, but that it could choose whether or not a victim was infected. Once this conversation was complete, the Didact, enraged about the revelation, fully activated the reverse stasis chamber, forcing an artificial decay process equivalent to a billion years to transpire over the course of several seconds, killing the Primordial, and breaking its body down to a state of complete physical entropy. However, as the consciousness of the being was shared by individual Graveminds, the Primordial effectively lived on in the form of the Flood compound mind.
The Primordial was massive in size; the mold encapsulating the being on Charum Hakkor outlined a being approximately fifteen meters tall and eleven meters wide. When first witnessed by the Didact on Charum Hakkor, the creature was described as possessing an insectoid head, four arms, and two degenerate legs. A long, segmented "tail" was attached to the base of the skull, tipped with a two meter-long barb. Each hand had three fingers and a central opposable thumb. The face of the Captive has been likened to that of a eurypterid, or "sea scorpion," a creature that the Precursors had allegedly seeded on a number of planets. Its head was flattened, with oval compound eyes and insect-like mouthparts.
Later, aboard Installation 07, the creature was described as having a large number of legs which it held in a curled-up position similar to a spider. The creature's torso was described as "grossly fat," and its skin was covered in a glassy, crystalline coating; a fine powder often fell from its body, perhaps Flood spores or the same powder responsible for the original Flood outbreak. As a Gravemind, the Primordial was capable of shifting its physical form to an extent, such as rearranging its limbs.
 List of appearances
- Halo 3
- Halo: Cryptum (First appearance)
- Halo: Primordium
- Halo: Silentium (Mentioned only)
- Halo: Rebirth (Mentioned only)
- ^ Halo Waypoint: Halo: Cryptum Glossary
- ^ a b Halo: Primordium, pages 67-68
- ^ a b Halo: Cryptum, page 342
- ^ a b Halo: Primordium, pages 362-365
- ^ a b Halo: Silentium, pages 174
- ^ Halo: Silentium, page 222 ("What were they like-the Precursors-when we sent fleets to hunt them down and destroy them?" -"Unlike the Primordial, unlike the Gravemind on the rogue Halo. Unlike the Flood, almost certainly.")
- ^ Halo: Cryptum, page 120 ("An ancient construct ... or a captive")
- ^ Halo: Primordium, page 326
- ^ a b Halo: Primordium, pages 190-192
- ^ Halo: Silentium, page 224 ("The Graveminds suck experience from all sentient history. One of them did everything but absorb me. Saw right through me, understood every strategy I've ever devised. They've advanced far beyond the Primordial.")
- ^ Halo: Silentium, page 167 ("This being was not the Primordial I encountered on Charum Hakkor, but something else entirely-though it retained the Primordial's motives and thoughts and memories. It was a Gravemind-the Gravemind, more accurately. It was the Primordial's final act of revenge.")
- ^ a b Halo: Silentium, page 173 ("The one the Didact questioned on Charum Hakkor arrived on the margins of our galaxy nine million years before. That one was discovered by humans decades before the end of the war. We are the same.")
- ^ Halo: Silentium, pages 181-182 ("We were not then powerful enough to erase all evidence of the Precursors, to destroy their star roads and citadels and other artifacts. And so we left at least one Precursor behind, to live out dreams of vengeance and hatred, to lay down plans in cold and darkness at the heart of a lost asteroid-over millions of years.")
- ^ Halo: Primordium, pages 236-238
- ^ Halo: Cryptum, page 270-271
- ^ Halo: Cryptum, page 121
- ^ a b Halo: Silentium, page 33
- ^ Halo: Cryptum, page 250
- ^ Halo: Cryptum, page 326
- ^ Halo: Primordium, pages 364-367
- ^ Halo: Silentium, page 167
- ^ Halo: Cryptum, page 277
- ^ Halo: Cryptum, page 119
- ^ a b Halo: Cryptum, page 277
- ^ Halo: Primordium, page 108-109
- ^ Halo: Primordium, page 363