I know that the (unconfirmed) latest we'll get to see a stand alone Batman movie is 2019 and it might take even longer before they introduce the Joker, but hear me out.

Seth Meyers for the next Joker. I see his Late Night show and the man looks like he might go over the edge at any moment. I could see him easily playing the failed, sad stand up comedian Jack from one of the Joker's multiple origin stories. He has a history in comedy so he most likely has a well of darkness to pull from like most humorous people. I think he'd do great given the opportunity to let loose and get to play a complete psychopath. It might conflict with his show, but it'd be a win win for both studios if he did a phenomenal job. Just my thoughts.

Crispin Glover and dot... He don't look that he might go over the edge at any moment... he can play role which are over the edge in any moment.... Man is born for Joker role... Think about it... think about him ...

@valdemocnij: He has the look and the chops although age may very well be a factor. We need someone who could stay on as the clown prince of crime. Great suggestion.