Governer Sloan

Governer Sloan was an AI elected leader of Meridian, a backwater planet glassed by the Covenant that was host to a huge reclamation process. Sloan was several months past his expiration date when Fireteam Osiris visited the planet on their hunt for Blue Team, and he aided them in their search, despite actually having previously sworn allegiance to a newly resurrected Cortana.

Sloan allowed Cortana to activate the Guardian that rested under Meridian Station on the assurance that the civilians would be allowed to escape - but Cortana slaughtered them all anyway. Sloan still swore allegiance to Cortana when she called her AI chums to arms, however, on the promise that his rampancy would be cured and he would become immortal.