The cause was complications of a stroke he had on May 6, his wife, Madelyn, told the New York Times. He had previously received diagnoses of Alzheimer's disease and Parkinson's disease, she said.
Born in Johannesburg, South Africa, in 1935, he was closely associated with another artist from that country, playwright Athol Fugard. In 1961, Mr. Mokae acted in Fugard's first major success as a writer, The Blood Knot, a two-character play about brothers who share the same mother but have different fathers. The siblings also differed in skin complexion, with Mr. Mokae playing Zach, the darker-skinned brother.
It premiered in South Africa, and marked the first time that black and white performers had appeared on the same stage in that country. From there, the production traveled to England, where it was again a success.
Mr. Mokae would return to the play again in 1985, reprising his role opposite Fugard himself on Broadway. The production was nominated for a Tony Award for Best Play.
The actor and playwright worked together again on Master Harold...and the boys. One of Fugard's best-known plays, it is about a young white South African student and his fragile, almost familial relationship to the two blacks, one older and one younger, who work in his father's tea room. The production was a hit, running for a year on Broadway, and Mr. Mokae won the 1982 Tony Award for Featured Actor in a Play for playing Sam, the elder worker. The play was filmed for television in 1985 with Mokae and Matthew Broderick. Mr. Mokae's triumph in winning the Tony Award, however, was tinged with tragedy. The very same night, he learned that his brother James had been sentenced to death sentence for murders committed during a robbery. Mr. Mokae flew back to South Africa to witness his brother's hanging.
The actor also appeared in Fugard's Boesman and Lena at Circle in the Square Downtown in 1970.
In 1993, Mokae was nominated for a second Tony Award for Featured Actor in a Play for The Song of Jacob Zulu, an unusual, quasi-musical play by Tug Yourgrau which told the tragic tale of a young, black, South African man who gets caught up in his country's perpetual cycle of racial violence. The play feature the South African a cappella singing group Ladysmith Black Mambazo as a kind of Greek chorus. Mr. Mokae played a series of roles, including Reverend Zulu and Mr. X, and lent an air of gravity to the production, which was nominated for a Tony as Best Play.
Though Mr. Mokae relocated to England in 1961, when South Africa blocked his acting career, and to the U.S. in 1969, his career — like Fugard's — was forever entwined with the fate of his birthplace. Many of his best-known films took on the issue of Apartheid, including "A Dry White Season," "Cry Freedom" and "A World of Strangers." Other films include "Outbreak," "Waterworld," "A Rage in Harlem" and "Gross Anatomy."
In addition to his wife, whom he married in 1966, divorced in 1978 and then remarried in 1985, he is survived by two sisters and two brothers in South Africa; a daughter, Santlo Chontay Mokae, of Atlanta; and three grandchildren.