John Lee Mahin (August 23, 1902, Evanston, Illinois – April 18, 1984, Los Angeles) was a prolific screenwriter and producer. He was the son of John Lee Mahin, Sr. (1869-1930), a Chicago newspaper and advertising man, and Julia Graham Snitzler.
He was active in films from the 1930s to the 1970s. He worked on such films as Scarface and The Wizard of Oz, but his name does not appear on the credits to the latter film.
He was a friend and frequent collaborator of director Victor Fleming. They worked on ten films together.
Mahin also wrote the screenplay for Show Boat (1951), the Technicolor remake of the famous 1927 stage musical, which had previously been filmed in 1936. According to musical theatre historian Miles Kreuger in his book Show Boat: The History of a Classic American Musical however, Mahin retained most of the basic structure of the storyline, but little of Oscar Hammerstein II's stage dialogue, preferring to create his own. According to Kreuger, it was Mahin and producer Arthur Freed who introduced the plot device of keeping the lovers Magnolia Hawks and Gaylord Ravenal young at the end, rather than having them age forty years as in the original stage musical.
He was married to silent film actress Patsy Ruth Miller from 1937 to 1946.