Sinclair studied at Shortwood College for Women. After completing her studies, she worked as a teacher in Jamaica until 1966, when she left for New York to pursue her career in acting. Sinclair began acting with the New York Shakespearean Festival and at Joseph Papp’s Public Theatre.
She is best known for her roles in Cornbread, Earl and Me (1975), Convoy (1978), Coming to America (1988), Trapper John, M.D. (1980–1986), and the ABC TV miniseries Roots (1977).
Sinclair also voiced the character of Sarabi, Mufasa’s wife and Simba’s mother, in the Disney animated feature film The Lion King (1994).
A five-time Emmy Award nominee, Sinclair won the Primetime Emmy Award for Outstanding Supporting Actress – Drama Series for her role as Empress Josephine in Gabriel’s Fire in 1991. –Wikipedia