Gunn was born October 2, 1929 in St. Louis, Missouri and earned his Bachelor of Arts degree from Tennessee State University in 1959. He then studied at the University of Kansas from 1959 to 1961 in their graduate program for speech and drama. Gunn made his New York stage debut in 1962 in “The Blacks” and went on to win Obie (Off-Broadway Theater) Awards for his performances in “First Breeze of Summer” (1975) and “Titus Andronicus” (1987).
He also was nominated for the Tony Award as Best Actor in 1976 for “The Poison Tree.” Gunn was a co-founder of the Negro Ensemble Company in the 1960s. Gunn also appeared on film with roles in “Shaft” (1971) and “Shaft’s Big Score” (1972) and in 1977 he was nominated for the Emmy Award for Outstanding Lead Actor for a Single Appearance in a Drama or Comedy Series for his role in the television mini-series “Roots.”