The Architect

"The Architect" was a fragment of abstracted personality. It was destroyed by Flood-infected battleship that had destroyed the Forerunner vessel that was ferrying it to the Ark.

"The Architect" is the core believed to have supported the Flood civilization by maintaining the habitats they overthrew, as well as selecting the locations that the parasite would colonize and construct hives, etc..

History
In order to prevent Mendicant Bias from subverting or harming him, Offensive Bias had shattered of Mendicant Bias into its component sections and scattered them throughout the few remaining ships of his fleet for transport to Installation 00, where he would study the fallen AI construct. Much of his fleet was destroyed or ravaged by the Flood. "The Architect" was destroyed in this manner.