Daddy Dominus

 was the Leader of the human Colony on Urth who demanded devotion. He delighted at torturing people. He created a religion that humans are the ultimate perfection of Urth and that the disease came from the Devil. He realised that being the leader was torture but the First Doctor reminded him that he wanted it in the first place. He explained why he ruled in such ways to get his society to actually work for the people. He eventually gave in. (AUDIO: For the Glory of Urth)