Black Mask was once Gotham's biggest crime lord and a throwback from the bad old days before Batman began his war on organized crime. A power-hungry sadist who used cold-blooded torture to get what he wanted. The emergence of costumed freaks eventually cost him his power and forced him out of the city for several years. Now, with the recent destabilization of Gotham's super community, he's back and planning to pick up where he left off.
This character has so far exclusively appeared in the Harley Quinn: The Animated Series - Legion of Bats! spin-off comic series.