"Joker" didn't work for Joker (and neither did "Suicide Squad" or "Birds of Prey and the Fantabulous Emancipation of One Harley Quinn")! "Maleficent" didn't work for Maleficent! "Hannibal" didn't work for Hannibal! I cry foul!
Maleficent was the hero of Maleficent, not the villain. Suicide Squad should be an accepted answer for Joker, and I suppose technically Joker as well (though he's the protagonist and arguably an anti-hero, not a villain), but he wasn't in Birds of Prey.