4. Dr. Arthur Arden American Horror Story: Asylum
In American Horror Story, we learn quickly that the seasons are connected, even in small ways. And Dr. Arthur Arden, who at one point was known as Hans Grüper, is absolutely a part of this series in multiple villainous ways.
While we primarily met Dr. Arden in Asylum, he was also in Freak Show (although as a young man). He is a Nazi doctor and is responsible for the snuff film that resulted in Elsa Mars losing both of her legs. But his horrors do not stop there. Far from it.
Technically, it is hard to rank the top four of this villains list because they are all equally horrible. And with Dr. Arden and his time on Asylum, we get a man willing to experiment on people for what seems like fun. He is responsible for creating altered humans who can be found roaming in the forest outside of the asylum. He tortured the patients of the asylum under the guise of science and scientific findings. He refused to use any anesthesia because he believed it would negatively impact his results.
He was a man who truly seemed to get off on torture. And if the people he experimented on died, it was no loss to him, because it seemed like there was always another victim for him to use and murder.
Arthur Arden is a killer and a monster. He gives villains a bad name.