Angus Roy MacPhail (8 April 1903 – 22 April 1962) was an English screenwriter, active from the late 1920s. He is best remembered for his work with Alfred Hitchcock.^[1]

Son of merchant clerk Angus MacPhail and Fanny Maud (née Karlowa), he was born in Lewisham,^[2] London, and educated at Westminster School and Trinity Hall, Cambridge where he studied English and edited Granta. At Cambridge, he was a close friend of fellow Old Westminsters Ivor Montagu, later a filmmaker, who described MacPhail as "a red-haired and rather gauche Scot from Blackheath", and Arnold Haskell, later a dance critic and headmaster of the Royal Ballet School.^[3][4]

He began to work in the film business in 1926, writing subtitles for silent films. He began writing his own scenarios for Gaumont British Studios and later Ealing Studios under Sir Michael Balcon. During World War II, he made films for the Ministry of Information. MacPhail wrote a number of screenplays for director Alfred Hitchcock. One of the latter's favourite devices for driving the plots of his stories and creating suspense was what he called the MacGuffin. His old friend Ivor Montagu, who worked with Hitchcock on several of his British films, attributes the coining of the term to MacPhail.^[5]