William Harrison Gunn was an American playwright, novelist, actor and film director. His 1973 cult classic horror film Ganja and Hess was chosen as one of ten best American films of the decade at the Cannes Film Festival, 1973. In The New Yorker, film critic Richard Brody described him as being "a visionary filmmaker left on the sidelines of the most ostensibly liberated period of American filmmaking." Filmmaker Spike Lee had said that Gunn is "one of the most under-appreciated filmmakers of his time." Gunn's drama Johnnas won an Emmy Award in 1972.

Ganja & Hess is a 1973 American black horror film written and directed by Bill Gunn and starring Marlene Clark and Duane Jones. The film follows the exploits of anthropologist Dr. Hess Green (Jones), who becomes a vampire after his intelligent but unstable assistant (Gunn) stabs him with an ancient cursed dagger. Green falls in love with his assistant's widow, Ganja (Clark), who learns Green's dark secret.