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.

It is one of only two films in which the lead role was played by Jones, best known for starring in the 1968 film Night of the Living Dead (though he had bit parts in other movies). The film was screened at the 1973 Cannes Film Festival. It was remade by Spike Lee in 2014 as Da Sweet Blood of Jesus.

In 2024, the film was selected for preservation in the United States National Film Registry by the Library of Congress as being "culturally, historically, or aesthetically significant".