This man is evil to the core:
In all seriousness he was just punishing a thief, but the way he stood there always rubbing his hands together, and how the fuck does he have the most powerful attack in the game? dude had some shady back story we never got to hear.
Everrett in Deus Ex was pretty evil, keeping Luscius on ice to satisfy his own ends:
Evil incarnate right here:
Another fearsome large lady:
Yeah, we have already had Shodan but she/it is a special case:
Rupture Farms were portrayed as evil but they were basically no worse than humans:
Jeannie May Crawford was an evil bitch. Luring her out for sweet head popping justice is the go-to:
The winner probably has to be Vault-Tec though: