Scorponok

Dangerous, wily, and cunning, Scorponok (aka MegaZarak and BlackZarak) possesses both a keen mind and a great deal of raw, savage power. He is equally comfortable with maverick stratagems and brute force, though he's built more for the latter: his animalistic alternate form bristles with weapons, from multiple paired cannons and the dreaded electro-stinger in his tail, to the crushing grip of his mighty claws. These traits combine to make him both a terrifying foe on the battlefield and a serious contender for leadership of the Decepticons. Often, only his arch-foe Fortress Maximus is capable of standing against him.

(Source: TF Wiki)