Galvatron

Galvatron is a cold-hearted robotic villain. Revealed to be Megatron reformated by Unicron because his body was badly damaged during his last fight Optimus Prime at Autobot City. Determined to lead the Decepticons and destroy Cybertron since the Autobots took it back from the Decepticons, forcing them to abandon their Earth base and retreat to the planet Charr, which would result in disposing of Megatron's dream of reviving Cybertron. Possesses enough strength to pulverize an Autobot into scrap metal. Unconquerable. Arrogant and compassionless. Plots against his allies, thus weakening his position. In robot mode, he carries a fission laser cannon that emits chemically-produced, direct-current electricity. Ever since Cyclonus and the Sweeps removed him from the plasma lava on the planet Thrull, the lava went into his head casing and he was permanently driven insane that he transformed into cannon mode in space and because the lava increased his strength, the planet Thrull was destroyed when Galvatron blasted it with a single shot. However, his insanity was temporailly gone at the ending of "The Return Of Optimus Prime Part 2" when the newly returned original Autobot leader unleashed the power from the Matrix Of Leadership to destroy the Hate Plague. Unfortunately, the Matrix was permanently rendered empty because Rodimus Prime used some of the Matrix's power to make Unicron's body explode at the ending of the animated movie. Because of it, Galvatron shook hands with Optimus, declaring the war was over and that Optimus had earned Galvatron's respect. But, at the beginning of "The Rebirth", Galvatron revealed he was still insane.

(Source: Wikipedia)