6. Mad Hatter
Jervis Tetch was diagnosed by Arkham's, Dr. Blakloch. In his diagnosis, it was noted that Jervis has an obsessive compulsion with hats that goes far beyond mere fascination. Aside from that, he is obsessed with the books of Lewis Carroll, Alice's Adventures in Wonderland and Through the Lookin Glass. His obsession leads to some pretty creepy places as it's been shown (in Secret Six) that he refuses to eat anything that doesn't have a hat on it, and further than that... has absolutely no interest in anything or anybody that does not wear a hat. He even debates the logistics of Batman's cowl and its status as a hat. He operates as an inventor, often inventing various methods of manipulation and mind control. He likes to stalk, kidnap, torture, and frequently emulates the Mad Tea Party chapter of Wonderland with his victims. Yes, he is known as a Batman-era villain. It isn't hard to see him existing in the underworld before.
Ideal Casting: In the comics and other media he has been known to look differently, short, fat, tall, lanky. I just want the creep factor to outweigh everything else. As Tetch I think the role would be best suited for former Prison Break-er, and Grimm cast member... Silas Weir Mitchell. He has that confident look of John Everyman, and he can play a good guy as well as a baddie, but picturing him with OCD twitches are beyond easy to see.