The Man Who Knew Too Much is a 1956 American mystery thriller film directed and produced by Alfred Hitchcock, starring James Stewart and Doris Day. It is Hitchcock's second film using this title, following his own 1934 film of the same name but featuring a significantly altered plot and script.

In the book-length interview Hitchcock/Truffaut (1966), in response to fellow filmmaker François Truffaut's assertion that aspects of the remake were by far superior, Hitchcock replied, "Let's say the first version is the work of a talented amateur and the second was made by a professional."

The film won an Academy Award for Best Original Song for "Que Sera, Sera (Whatever Will Be, Will Be)", sung by Day. It premiered at the Cannes Film Festival on April 29, 1956.