After his big battle with Optimus Prime in the 1986 movie, Megatron ,who was mortaly wounded, was thrown into space to make room for the surviving Decepticons, Starscream personaly oversaw his "kicking". After drifting through deep space, the mortaly wounded Megatron, was summoned by Unicron, who after a bit of forceful negociations, turned Megatron into Galvatron

Enjoy!