In The Dark Knight, the character Coleman Reese has a 'theory' about why Bruce Wayne is always tired when he shows up for meetings. Later after failing to blackmail Mr. Fox, his life is threatened by The Joker. Well blah blah blah you've all seen the movie. But what some of you didn't notice is that he is referred as "Mr.Reese"...think about it long and hard if you don't get it. Are you ready? MYSTERIES!!!
My guess is that Coleman Reese was secretly working for The Joker and was his protege, and now that Reese is aware of Bruce Wayne's alter ego and with Joker in prison, it gives Reese the opportunity to take the matter into his own hands.
So in conclusion, actor Joshua Harto will portray The Riddler.
Talk amongst yourselves :)