The Weapon (Halo Infinite)

An AI developed prior to the events of Halo Infinite, tasked with locking down and deleting Cortana before she could bring further destruction to the galaxy through her armada of Forerunner Guardians. She was supposed to auto-delete afterwards since she was created in the exact same circumstances as Cortana, but Master Chief decides to keep her around after Cortana is gone. The Weapon serves as the Master Chief's AI companion over the course of the game.