10 Times Superheroes Defeated Themselves

Superboy-Prime, for all his faults, is put into a pretty difficult situation at the start of Infinite Crisis. He's trapped in a universe that's not his own, unable to ever go back to the people he cares about and who love him, and aware the whole time that he will never be considered the 'real' Superboy of the universe he inhabits, because there already is one, in the form of Conner Kent.

This causes tension between the two superpowered boys, culminating in Superboy-Prime going off the deep end and trying to kill Conner - accidentally actually killing some Teen Titans along the way, which begins his descent to complete villainy.

While Conner would die in the pair's final fray, he would do so by flying himself and Superboy-Prime into the Anti-Monitor Tower the villain had made, wiping out the source of his seeming invulnerability - and saving the world at the same time, which counts as a pretty big victory, even if it took other heroes to finally down Superboy-Prime.