Offensive Bias

Offensive Bias was a mean AI that the Forerunners created to stop the 'rampant' Mendicant Bias from destroying their fleet. He is known for being very insulting, and as soon as he was created he insulted the three top Forerunner scientists on thier weight, height, density and intelligance before someone could switch him off. All three scientists then commited suicide.

He was put in charge of the Forerunner Fleet, and used it as a massive bomb to destroy that opposing fleet. During the fray, he somehow captured Mendicant Bias and took him back to the Ark. He dismantled Mendicant and spread his pieces all over the Galaxy via the reseeding ships, then disappeared, never to be seen again.

Well, apart from 102,000 years later when he popped up at a League meeting. It should be noted that, whereas Mendicant's design was based on a Monitor, Offensive's design was based on a Promethean Watcher, suggesting that the Didact had more to do with Offensive than it initially seems.