Batman: Hush

Boy, this should be entirely adapted on the big screen. From all the (relatively) newly introduced villains, Hush is the most iconic one. With a backstory mirroring the one of Bruce Wayne, Thomas Elliott's story needs to be told.

Batman: Hush is also one of the storylines that features multiple villains. Unable to go toe to toe with Bruce Wayne, Hush would need some serious muscle behind him. And, again, Clayface is more than welcome for a first appearance on the big screens.

Basically, Thomas Elliot, as a long-time friend of Bruce Wayne, saves the billionaire and realizes everything about his secret identity. Scheming against him and using various villains, he actually has the upper hand, until Harvey Dent shoots him.

Hush falls, apparently, to his death, but his body is never found. So Hush could be the villain to pop up all over the place in a new Batman trilogy.