Um, professor umbridge from Harry Potter. She’s basically an asshole just to be one.

The other ones all have some sort of justification to their shittyness. Jenny was abused, Vader was a literal slave that was taken advantage of by both the Jedi and palpatine. The joker has literal mental issues.

Umbridge was straight up a child abuser with no remorse or tragic back story. She harmed kids while enjoying it and drinking tea.