Leonard Cyril Deighton is a British author. His publications have included cookery books and works on history, but he is best known for his spy novels.

The IPCRESS File is Len Deighton's first spy novel, published in 1962. The story involves Cold War brainwashing, includes scenes in Lebanon and on an atoll for a United States atomic weapon test, as well as information about Joe One, the Soviet Union's first atomic bomb. The story was made into a film in 1965 produced by Harry Saltzman, directed by Sidney J. Furie and starring Michael Caine; and a 2022 TV series, starring Joe Cole, Lucy Boynton and Tom Hollander.