Megatron

"You still fight for the weak. That is why you lose!"
- Megatron to Optimus Prime. Megatron was once brothers-in-arms with Optimus Prime, appointed to be Cybertron's Protector and commander of its Defense Force. But Megatron resented his comrade, Optimus was a Prime and therefore not as favored. This anger allowed The Fallen to corrupt him and led to the revival of the Decepticons and start a war that has lasted for millennia. Now he only seeks to obtain the AllSpark to reform Cybertron at his image and rule the universe.