I thought of another one:

Brock Lesnar in WWE Smackdown Here Comes The Pain on PS2

That ahole was next to unstoppable! I play those games on their hardest difficulty (I find them quiet easy) but even on normal this guy was a bastard. I remember he used to be able to kick out of your finisher even when his body damage was in the red. I really really hated ever playing against him the dirty smurfer!