Terry Gilliam is the only full-time Monty Python member who is not of any U.K. origin. In fact, he is American, and was originally hired because of his artistic talents. He then became more than just a background character on-stage.
Terry Gilliam was the co-director of Monty Python and the Holy Grail (1975). He also gained much critical acclaim from all of the amazing movies he directed and sometimes wrote either in part, or in total, the screenplay. One such movie that got his first critical acclaim is Brazil (1985).
The first person to leave the Pythons was John Cleese. He became widely renowned in the U.S. from his work in Monty Python movies. He began to get paid more to keep him, which caused tension amongst the cast.