User blog comment:AustinDR/Moral Agency/@comment-32931283-20171009182807

yet Joker qualifies - he's criminally insane and shown in many cases to be among THE most insane characters in DC.. full stop.. so mental illness seems like something not used often.

in fact a truly evil character is almost always severely mentally ill as no sane creature goes around killing, raping and ruining societry the way CMs do.