The Third Secret is a 1964 British CinemaScope neo-noir psychological mystery thriller film directed by Charles Crichton, and starring Stephen Boyd, Jack Hawkins, Richard Attenborough, Diane Cilento, Pamela Franklin, Paul Rogers and Alan Webb. The screenplay by Robert L. Joseph focuses on an American newscaster who investigates the mysterious death of his psychoanalyst. According to the film, there are three kinds of secrets; the first, you keep from others; the second, you keep from yourself, and the third is the truth.

Charles Ainslie Crichton was an English film director and editor.