Limiting it down to one?
Who's the Creeper, you ask? He's a character from DC Comics.
Jack Ryder is a reporter in Gotham City. Once upon a time he ran across the wrong bad guys, a mad scientist and a Halloween costume. The end result its that when Jack Ryder touches a device planted in his arm, he becomes the Creeper.
So what it is about the Creeper? He's a good guy with just a slight twist of the Joker thrown in to add to madness. He MIGHT have some DNA from the Joker. he MIGHT have a few supernatural twists. He definitely runs toward the crazy side and he can be horrifically violent. I ask you, what's not to love?
The Creeper was created by Steve Ditko, the very same gentleman who created Spiderman along with Stan Lee. He is disturbing and off the rails in the best possible ways. There is so very much I'd like to explore about him and so many tales I would love to tell. I think he could be a unique Gothic hero in Gotham of all places. A chap who handles the things that Maybe Batman doesn't get around to seeing. And that says a lot as Batman is the world's greatest detective.
Oh, and in a pinch I'd gladly work on Batman. :) Or the Joker for that matter.