Another installment of who i think would be good as The Riddler in another Batman movie franchise:
Johnny Depp:
I have to admit i put Johnny Depp on the list because i think he can do it and another out of respect casting, sometimes Depp's roles feel the same i do think if a director pushed him to his limits and Depp does the proper research then the role is in the bag.Robert Downey Jr.
While im pretty sure this could probably never happen but his role as Sherlock Holmes could be the perfect background and flipping that into a psychotic villain character would be the perfect range for Downey as i feel he would do the role justice... or should i say riddles.