Answer: They're villains of Batman (in the TV show)
Everyone who answered got it; some got it down to that they were TV villains, but the answer in parens is just additional info, not required, so I didn't ask everyone to be more specific. So pretty much everyone who's been playing the game gets a point: DarthFerret, EricBess, Limited, Melkor, Mooseman, mythosx, Oversoul, Ransac, rokapoke, sageridder, TomB, train, turgy22
Scores:
EricBess: 20
TomB: 18
train: 18
Oversoul: 17
Ransac: 17
rokapoke: 17
sageridder: 17
DarthFerret: 16
Melkor: 16
Mooseman: 14
turgy22: 14
Limited: 9
mythosx: 9
Lythand: 6
cardboardbox: 0