The international blog of webcomics: Waffle has a post on webcomic problems. Adam Cuerden lists some of the wrong turns a creator can make with a character, particularly the sins of making your protagonist "godly".
1. "The Chosen One": Suddenly, your ordinary character is the only one that can save the world, and he'll need to work hard to get the incredible amount of power he needs to save it….
2. The stupid weakness: He may be all-powerful, but the colour yellow makes him useless. Er, unless he tries really hard to overcome it.