2. Lex Luthor
Lex Luthor?! In Batman?! Its not unheard of, at least not in the comic book DC Universe. And what better way to start setting up or of course continue to build an expanded DC Film Universe in preparation for a Justice League movie?
How it Could Work: He could enter the story as an organic progression from Nolans movie by championing to help restore Gotham after the damage caused by Bane (whilst also having a dastardly scheme up his sleeve of course). He could also be inserted as part of an entirely new plot one in which hes sick of being thwarted by Superman, and attempts to relocate to Gotham under the mistaken belief that Batman will be easier to outwit.
Who Could Play Him: You want a guy that does authority and arrogance well. As an outside choice I wouldnt necesarrily be averse to seeing
Benedict Cumberbatch in the role (wearing a bald-cap of course) but for a more straight choice Id be tempted to go for someone like
Ralph Fiennes or possibly even
Billy Zane.
Likelihood: You never know. With the Justice League movie all but happening for certain, Warner Bros. will almost definitely look to create some sort of extended Universe, as Marvel did on the road to The Avengers. Casting a supposed Superman rogue as a main Batman villain would certainly serve to achieve this. And if thats the case, you know what could feasibly happen next right?