Samuel Guy Endore (4 July 1900 - 12 February 1970), also known as Harry Relis, was a novelist and screenwriter. He wrote many novels and screenplays for action films and thrillers. He is best known for his novel The Werewolf of Paris which occupies a significant position in werewolf literature, in much the same way as Dracula does for vampires.
He was nominated for a screenwriting Oscar for The Story of G.I. Joe (1945). Endore's novel Methinks the Lady . . . (1946) was the basis for Ben Hecht's screenplay for Whirlpool (1949).
Endore was a committed leftist and was investigated by the House Un-American Activities Committee during its search for Communist infiltration of the film industry. Some studios thus blacklisted him and he had to sell his screenplays under the pseudonym Harry Relis (Relis was actually the husband of Endore's wife's eldest sister). He remained defiant, however, claiming that he was a failure as a human being if he was not subversive to everything HUAC stood for.