1. The Riddler
Why: Lets get the obvious one out the way first. Edward Nygma, aka Riddler is a notorious presence within the Batman underworld. He is perfect for Nolan and is, in all honesty, very close to the type of criminal Nolan has chosen for TDKR. He is super intelligent, visually brazen (in comparison with Banes gorilla-like mask), flourishes when tormenting Batman and thrives on destruction. The only major difference between Bane and Riddler is physical strength.
How: The Dark Knight was a film about chaos, watching the world burn but The Joker was extremely well organised in his approach. An interesting development for TDKR would have been to reveal that Riddler was pulling the strings all along. Batman has dealt with fear, then chaos; so what better way to end the trilogy than to have him deal with a highly rational criminal mind?
Who: Robin Williams. He has been very vocal in the past about playing the character, and does a great creep. Im thinking more One Hour Photo Williams than Aladdin Williams. His disarming appearance would make for an interesting compare to previous villains in the Nolan universe and he has already played a rather disturbed individual for Nolan in Memento.
