He may be best remembered in film for his portrayal of mobster Ellsworth Raymond "Bumpy" Jonas in the first two Shaft movies, Booker T. Washington in the 1981 movie Ragtime, a performance which won him an NAACP Image Award, and as Cairon, the Childlike Empress' imperial physician, in the 1984 film The NeverEnding Story. He was nominated for an Emmy Award in 1977 for his role in the TV mini-series Roots. He also co-starred with Avery Brooks on the TV series A Man Called Hawk. Gunn appeared in six episodes as atheist shop owner Carl Dixon on Good Times, as boxer-turned-farmer Joe Kagan on Little House on the Prairie, and as "Moses Gage" in Father Murphy. In 1989, Gunn appeared in two episodes of The Cosby Show as two different characters. His final acting role was as murder suspect Risley Tucker in "Three Men and Adena", an episode of Homicide: Life on the Street.