Galvatron

When Galvatron, the self-proclaimed "new" Emperor of Destruction, deigns to storm the battlefield, the Maximals know to run in the other direction. His ambition is as boundless as it is terrifying; Galvatron is a villain perfectly willing to annihilate entire planets and harness the lifeforce of primeval gods simply as a means to an end. A juggernaut on the battlefield in either his drill tank or dragon modes, opposing forces have found that he's an enemy who cannot be destroyed, merely contained or temporarily waylaid. And yet, no matter how deeply his enemies bury him, no matter how sure they are that "he's gone for good"... Galvatron always comes back.
(Source: TFwiki)