The other name Stephens threw into the ring at WonderCon was Clayface, a character that's a fair ways away from the Mad Hatter. Where that character's reasonably easy to pin down and bring to life on screen (just put a short guy with bugged-out eyes in an old Alice In Wonderland costume), and there's one characterisation that wins out above all others, Clayface is a bit of a mess. For one thing, there's been about a dozen bad guys with the name. For another...he's a big monster made of clay. Or at least, that's what the modern versions of the character have been. The dominant Clayface is Basil Karlo who, inspired by his interpretation in the classic nineties Batman animated series, was a supervillain who was turned into a clay monster...for some reason. It meant he was basically indestructible, and disguise himself by transforming his body. A bit larger-than-life for Gotham, but his early appearances might gel a little better. When he debuted in an early, pulpy forties Batman story he was a struggling actor driven insane by the cancellation of his first major project, going around killing other performers whilst wearing the mask he would've done in the canned horror flick. That's way more Gotham's speed.
Tom Baker is the Comics Editor at WhatCulture! He's heard all the Doctor Who jokes, but not many about Randall and Hopkirk. He also blogs at http://communibearsilostate.wordpress.com/