[Phoenix1010]

For RPGs I'd have to say Velius from FF Tactics. His fight is somewhere in the middle of the game, and there's an unexitable save point right before it. He's tough. So tough in fact that if you've just been going along with the story and not done any extra leveling, there's a decent possibility that you have no chance of beating him. And if you used the save point right before him, you can't get out to do more leveling. So it's a boss so powerful that it makes you restart the whole damn game. I know two people who had to do this, and it was hilarious each time.