Waldo Pressman Salt (October 18, 1914 - March 7, 1987) was an American screenwriter who was blacklisted by the Hollywood movie studio bosses during the era of McCarthyism.

Born in Chicago, Illinois, Waldo Salt graduated from Stanford University at age eighteen. The first of his nineteen films he wrote or in which he participated in the writing, was released in 1937 with the title "The Bride Wore Red." He joined the American Communist Party in 1938. He was a civilian consultant to the U.S. Office of War Information during World War II.

Salt's career in Hollywood was interrupted when he was blacklisted after refusing to testify before the House Committee on Un-American Activities in 1951. Like many other blacklisted writers, while he was unable to work in Hollywood Salt wrote pseudonymously for the British television series The Adventures of Robin Hood.

After the collapse of the blacklist, Salt won Academy Awards for Midnight Cowboy and Coming Home, and a nomination for his work on Serpico.

Waldo Salt died in Los Angeles in 1987. He is the father of actress Jennifer Salt.

Waldo Salt was one of the many people blacklisted in Hollywood during the Red Scare, but unlike others, Salt recovered triumphantly. He wrote his first scripts in the late 1930s (MGM contract writer, 1936-42) and also served as a civilian consultant to the Office of War Information from 1942- 1945 before being blacklisted in 1951 after refusing to testify before HUAC. Salt spent several years writing under assumed names for various television series (low-budget series such as "Colonel March of Scotland Yard," for example) and undistinguished films before slowly turning his career around, working in more widely seen television and eventually winning two Oscars for his later work in film.