Cartman is a ruthless, conniving, manipulative jerk who has zero redeeming qualities. And if he's that bad whilst in elementary school, imagine what an adult Cartman with full use of his powers would be like? Throughout the long and illustrious run of South Park, he has proven remarkably willing to abandon and betray his closest friends with nary a second thought. He's a racist, cruel momma's boy who, on a consistent basis, has shown a complete lack of a conscience. But what makes Cartman a great villain is not that he's a brat (because really, that's hardly a rare commodity in the nine year old boy population), but how successful his nefarious efforts are. For a little kid, he can do a shocking amount of damage. Without his best friends to rein him in, he is a loose cannon and a force to be reckoned with. And God forbid you ever mention his weight to him.