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 a Precursor and a Gravemind, a manifestation of the Flood collective consciousness.
The exact origins of the Primordial remain a mystery. It is known that following their defeat at the hands of the Forerunners, 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. It appears likely that the Primordial was one of these mutated Precursors, having failed to reconstitute itself properly and instead having transformed into a parasitic monstrosity - one of the first Graveminds.
As a Gravemind, the Primordial was formed from multiple Flood-infected hosts; the exact number was never determined, but Forthencho theorized that there had been at least twelve. Along with the other remaining Precursors, the Primordial decided upon a plan to re-unify Forerunners and humans. The exact nature of this plan remains largely unknown, but it is known to have involved the Flood.
The Primordial arrived in the Milky Way galaxy 9.1 million years ago. 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 some time after humanity colonized the planet, 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, Yprin 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. It was 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.
When the Flood were first encountered in the Milky Way, several humans questioned the prisoner as to the nature and origin of the "disease". When the prisoner gave them an answer, 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. It told the Didact that it was the last Precursor, and that the Forerunners had rebelled against the Precursors. The Didact revealed this information to no one with the exception of his wife, the Librarian.
When the Contender-class artificial intelligence Mendicant Bias tested Halo Installation 07 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.
During this time period, Mendicant Bias conversed with the Primordial, who in turn explained the purpose of the Flood, the nature of the Mantle, and the eons-long plan of the Precursors. During the course of this conversation, it soon became clear that the Primordial was in actuality a Gravemind, a physical embodiment of the Flood's collective consciousness. Mendicant Bias was eventually persuaded by the Primordial/Gravemind's arguments, and deliberately succumbed to rampancy. The AI then defected to the Flood, and referred to the Gravemind as its master, demonstrating its denial of the Forerunners.
- "It is your task to kill this servant. That another may be freed."
- —The Primordial speaking to the Didact.
After reclaiming Installation 07, the Didact imprisoned the Primordial, and alongside the wounded Chakas, interrogated the entity. During the course of their conversation, they came to realize that the Primordial is 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 are 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.
The Primordial was massive in size; the mold encapsulating the being outlined a being approximately fifteen meters tall and eleven meters wide. Originally when first witnessed by the Didact on Charum Hakkor, the creature was said to possess an insectoid head, four arms, and two degenerate legs. However, 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.[note 1] 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. 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.
 List of appearances
- Halo 3
- Terminals (As the Gravemind)
- Halo: Cryptum (First appearance)
- Halo: Primordium
- Halo: Silentium (Mentioned only)
- ^ As a Gravemind, the Primordial was capable of shifting its physical form to an extent (such as rearranging its limbs), explaining the different number of legs.
- ^ Halo Waypoint: Halo: Cryptum Glossary
- ^ Halo: Primordium, pages 67, 68
- ^ a b Halo: Cryptum, page 342
- ^ a b Halo: Primordium, pages 362-365
- ^ Halo: Primordium, page 326
- ^ Halo: Silentium, String 13
- ^ Halo: Cryptum, page 250
- ^ Halo: Cryptum, page 270-271
- ^ Halo: Cryptum, page 121
- ^ Halo: Cryptum, page 326
- ^ Halo: Primordium, pages 364-367
- ^ Halo: Cryptum, page 277
- ^ Halo: Primordium, page 108-109
- ^ Halo: Cryptum, page 119
- ^ a b Halo: Cryptum, page 277