James Neville Mason (; 15 May 1909 – 27 July 1984) was an English actor. He achieved considerable success in British cinema before becoming a star in Hollywood. He was the top box-office attraction in the UK in 1944 and 1945; his British films included The Seventh Veil (1945) and The Wicked Lady (1945). He starred in Odd Man Out (1947), the first recipient of the BAFTA Award for Best British Film.

Mason starred in such films as George Cukor's A Star Is Born (1954), Alfred Hitchcock's North by Northwest (1959), Stanley Kubrick's Lolita (1962), Warren Beatty's Heaven Can Wait (1978), and Sidney Lumet's The Verdict (1982). He also starred in a number of successful British and American films from the 1950s to the early 1980s, including: The Desert Fox (1951), Julius Caesar (1953), Bigger Than Life (1956), 20,000 Leagues Under the Sea (1954), Journey to the Center of the Earth (1959), Georgy Girl (1966), and The Boys from Brazil (1978).

Mason was nominated for three Academy Awards, three Golden Globes (winning the Golden Globe in 1955 for A Star is Born) and two BAFTA Awards throughout his career. Following his death in 1984, his ashes were interred near the tomb of his close friend, fellow English actor Sir Charlie Chaplin.