King of All Cosmos. He once got drunk and destroyed the galaxy, and his attitude about it suggests it may not be the worse thing he's done. From Katamari Damacy.
LeChuck. An apparently immortal Pirate King in command of an army of the undead and powerful voodoo magicks. From Monkey Island.
Revolver Ocelot. Has been screwing over world governments since he was old enough to have a codename. From Metal Gear Solid.
Sonic the Hedgehog. Quite possibly the most powerful fictional hedgehog, with both super-hedgehog abilities like incredible speed, jumping ability, and ATTITUDE, but also potential invincibility due to his collection of rings. He can also do that Dragonball thing with the yellow hair and fly.

Hmm, looks like Sonic is out.

Bet you're happier I gave you your Mario vs Sonic battle early now JMickle :)