4. The Joker
Heath Ledger's performance as the Joker will remain as the all time gold standard for acting in a comic book film but, eventually The Clown Prince of Crime has to return. He is too big of a draw in theatres and one of the few villains that could twist things around and put Batman and Superman at each others throats. If the Joker is to return this could be the stage, coupled with another villain who would be physical threat and possibly Harley Quinn's big screen debut, there's plenty of reasons to get excited. There will always be those people who say there shouldn't be another actor to play The Joker and that could be true. No one wants to follow that performance. But I for one, would love to see Superman go blow for blow with Batman as The Joker maniacally laughs looking on from safety. The draw back would be that with the god-like Supes in Man of Steel and his obvious moral flexibility (Zod was probably as surprised as us) the whole time many people would be thinking that he should just just kill him.