Sentinel Prime is the hidden main antagonist of Transformers: Dark of the Moon. He can transform into an airport fire truck. Sentinel Prime was originally an Autobot, but he betrayed the Autobots and became a Decepticon; so that he could save Cybertron. The movie's title Dark of the Moon is a reference to him and his space bridge pillar technology that forms the plot. Sentinel's ruthless motives and selfishness towards both Optimus and Megatron led to his own death.