Autobots

Sentinel Prime was a turncoat Autobot Commander and a double agent. He mentored Optimus Prime. He was always patriotic to a fault towards Cybertron, and was a strong willed and determined leader, who held a firm belief in the position of his race in the universe, and demanded respect from all around him, which he earned by proving himself a fierce and powerful warrior. Sentinel was charged with the safety of his secret weapon, the Pillars, which he believed could save their dying planet. Eventually, his hopes to revive Cybertron to its golden age glory changed him, and he ultimately betrayed the Autobots to secure Cybertron's survival, but he was killed by Optimus in a final duel at the Battle of Chicago

Sentinel uses the Pillars to transport hundreds of concealed Decepticons from the Moon to Earth. However, he betrays them, revealing that he made a deal with Megatron to ensure Cybertron's survival. Sentinel kills Ironhide, steals the Pillars, and escapes.

They are nearly killed by the Decepticons before the Autobots intervene. It turns out that the Autobots faked their death to gain an advantage over the Decepticons.

Megatron then falsely offers a truce, but Optimus refuses and kills Megatron by decapitating him. Sentinel tries to reason his actions to Optimus but is executed by him for his betrayal. Sam and Carly are reunited, and the Autobots remain on Earth as their permanent home.