@Chialikesreddit13 He's not quite as heinous as those two or many other PE villains in terms of sheer numbers, but I think what makes him still worthy of being deemed as one of the most evil villains is just how evil he is as a person.
Like between the sheer barbarity and disgust of his acts, the lack of reasoning behind many of them, the extreme sadism he feels about them, and his extremely twisted philosophy, he still stands out as a particularly vile villain in my eyes.