5. The Riddler
The Riddler's reputation may have been damaged by Jim Carrey in Batman Forever, irreparably some would claim, but there is no doubt that he is one of Batman's greatest foes, with his inclusion in the videogames Arkham Asylum and Arkham City leading to some of the game's most inspired moments in the form of his riddles and challenges. The Riddler could have been a highly intriguing character, with his cunning intellect he could have been the central villain of a Nolan Batman film, maybe setting up various crimes around Gotham, forcing Bruce to come up with answers to his riddles under strict time constraints in order to save innocent lives. If he doesn't seem that threatening himself once Bruce had caught up to him, he would have had a large gang under his control, maybe even a henchman in the form of Firefly, with many of the crimes his riddles alluded to being the fires that Firefly was starting. It could also have led to an interesting dynamic between the Riddler and Firefly; I can imagine Riddler setting up Firefly by giving Bruce an easy riddle in an attempt to protect himself. Whilst this is all obviously never going to come to pass in a Nolan Batman film, it would have been a brilliant prospect and one I would love to see explored further down the line in future Batman films, whilst lamenting that we will never see him grounded in the realistic Dark Knight trilogy. Thinking about it, if Batman began to really struggle with the riddles he was posed with, and began to give up hope of ever catching the criminal mastermind, who better to look to than the next entry on this list..?