Source: jaysbrickblog.com

7. Red Hood

Ah, the long and storied history of the Red Hood. A Batman villain who has a ton of credibility and respect, even though he’s had hardly any appearances.

The first Red Hood was introduced as a possible origin for the Joker. He was a standard criminal who looked like if Mysterio had formal wear until he encountered The Batman. Batman beat him up, and he wound up accidentally getting knocked into a vat of acid. That acid permanently disfigured his skin and face and drove him insane, turning him into…The Joker.

The second Red Hood was the formerly dead Robin, Jason Todd, who came back from the dead and decided to be a massive jerk by adopting the identity to keep his identity secret. He kept that ID, and has used it to this day in his work with The Outlaws (Bizarro and Artemis).

The third Red Hood is the New 52 version. He was first introduced in the Batman story Zero Year, as the leader of the Red Hood Gang, which was in operation during the first year of Batman’s existence.