He is best known for his performance as the apparently mute Chief Bromden in the 1975 film One Flew Over the Cuckoo's Nest and as Crazy Horse in the 1977 western The White Buffalo, as well as his roles as Taylor in Poltergeist II: The Other Side and Ten Bears in 1976's The Outlaw Josey Wales.

His specialty was bronco busting, and he was on the rodeo circuit when One Flew Over the Cuckoo's Nest producers Saul Zaentz and Michael Douglas were looking for a large Native American to play the role of Chief Bromden.

He had a recurring role on the TV series Vega$ as Harlon Twoleaf, and starred in the movies Fish Hawk, and Orca.

He also played Crazy Horse in The White Buffalo with Charles Bronson and the archetypal Elevator Attendant in Nicolas Roeg's 1985 film, Insignificance.

The episode pays homage to Sampson's work as Chief Bromden in One Flew Over the Cuckoo's Nest; Tim plays "Tonto" after Frank (Danny DeVito) is mistaken as mentally incompetent and placed within a facility.

[citation needed] Tim made a similar appearance in an elaborate Cuckoo's Nest parody set in a restaurant kitchen in the second series of the British sitcom Spaced.