2) Bizarro
Bizarro is one of those Superman terms that have managed to pass into popular culture (like Brainiac), with the word being used to describe anything that is the reverse of the norm. The character’s fame might be bigger than most Man of Steel villains, then, but he is still far too, well, bizarre to appear in a film.
In short, Bizarro is a twisted version of Superman, as bad as the Big Blue Boy Scout is good. Elements of the character have been used before, in the evil Supes of Superman III and Nuclear Man in Superman IV: Quest For Peace. However, Bizarro’s comic book origin, in which he comes from an alternate world where everything is backward (including the speech), was even too goofy for those movies. As such, now that Supeman films are much grittier, Bizarro’s chance at the limelight has most likely passed.