Sentinel Prime or known by Optimus Prime as The Great Sentinel Prime, is an alternate reality version of his Bayverse incarnation. He's heavily based on that version of the character; except in this universe Sentinel Prime realized his wrong doings and decided to rebel against Megatron. He is Optimus Prime's mentor and the second leader of the Autobots. Sentinel Prime is the former ally to Megatron and the Decepticons.