Offline
1027 Lex Luthor of the Justice Lords universe, JL
Offline
1032 Hades, JL
Offline
1082 Mad Hatter, Batman Bad Blood
Offline
1097 The Boss, Superman (1942 cartoon, Showdown)
Offline
1112 Anycard, Teen Titans
Offline
1113 Tony Zucco, The Batman
Offline
1123 Black Spider, Young Justice
Offline
1126 Killer Frost, JL Unlimited
Offline
1128 Red Hood, Batman Under the Red Hood
Offline
1150 Wizard, Young Justice
Offline
1176 Dwarfstar, Brave and Bold
Offline
1175 Uthool (possessing Batman), JL Action
Offline
1193 Tiger Shark, Brave and Bold
Offline
A couple answers I'm deeming close enough: Imperium is close enough to Imperium Leader. The other case is one of those situations I'll give you due to my lack of familiarity with the source material. For B&B Tigress, the B&B Wiki says that Artemis Crock (the character pictured) was being groomed by her mother (the previous Tigress) to be the next Tigress, which the DC Wiki says she did use the alias. Since I haven't watched, I'll allow that. Beyond that, everyone correct; list updated.
Offline
1048 Starburst, Static Shock
Offline
1278 Mad Hatter, Young Justice
Offline
1159 Ra's Al Ghul, BTAS
Offline
1171 Deadshot, Brave and Bold
Offline
1239 Catwoman, Return of the Caped Crusaders
Offline
1316 Minotaur, Super Friends
Offline
1301 Jax-Ur, Superman TAS
Offline
1310 Nostromos, BTAS
Offline
1280 The 50s Joker from Legends of the Dark Knight episode of BTAS
Offline
1282 Count Vertigo, BTAS
Offline
1283 Brand, Brave and Bold
Offline
1288 Bleez, GL
Offline
1289 Professor Chang, Teen Titans
Offline
1286 Livewire, JL Gods and Monsters
Offline
1274 Lex Luthor, JL Dark Apokalips War
Offline
1261 Black Manta, Young Justice