"I'm sorry, I forgot… you ignorant hicks have spent so much time playing banjo in the woods, you don't realize that I, Hercule, am the martial arts champion of the world!"
Sorry... I just love that quote above. And it sooo captures the mind-numbing arrogance the Martial Arts Champion of the world exhales as easily as carbon dioxide.
In Japan, he's Mister Satan (though I don't know whether Satan is his first name, last name, or stage name, ala' Hulk Hogan). In America, no doubt because of the connotations of the name Satan, he's Hercule. But whatever you call him, this warrior is a hoot! Don't get him wrong, though... he really is pretty strong. In fact, he very well may be the strongest warrior on the show that isn't part of Goku's little clique of superfighters. And before he faced Cell, he was absolutely assured of his superiority.
The Cell Game was humbling for Earth's champion. He's lucky he wasn't killed... but he didn't learn his lesson. Oh no... for Mr. Satan is nothing if not a great actor! He took credit for Cell's defeat, becoming an even greater celebrity. You'd think that eventually, this poser would have been uncovered. But no, the Z-Senshi aren't like that. In fact, Mr. Satan manages to survive Budokais against marvelous fighters, maintaining his title as the world's champion. He even survived the fight against Majin Buu... and actually helped Goku and company save the world.
So, all in all, Mr. Satan isn't a bad guy. He's obnoxious, arrogant, and a notorious liar and glory hog... but he's a good man and valuable ally when it really counts.