Starscream (Generation One)

Starscream is a Decepticon from many different continuities of the Transformers universe. An ambitious and treacherous sort of fellow, he most often gets his chance to lead after backstabbing or betraying Megatron in some form.

Generation One
Starscream is one of Megatron's most trusted lieutenants, even if he's always trying to usurp Megatron's leadership. He finally gets his chance to lead after throwing a critically injured Megatron out of an airlock into the vastness of space. His leadership reign doesn't last past his coronation ceremony however, as Galvatron quickly crashes the party and vaporizes him.

This does not deter Starscream from tormenting Galvatron, for at this point, he became a ghost.