Fantastic Voyage is a 1966 American science fiction adventure film directed by Richard Fleischer and written by Harry Kleiner, based on a story by Otto Klement and Jerome Bixby. The film is about a submarine crew who is shrunk to microscopic size and venture into the body of an injured scientist to repair damage to his brain. In adapting the story for his script, Kleiner abandoned all but the concept of miniaturization and added a Cold War element. The film starred Stephen Boyd, Raquel Welch, Edmond O'Brien, Donald Pleasence, and Arthur Kennedy.

Bantam Books obtained the rights for a paperback novelization based on the screenplay and approached Isaac Asimov to write it.

Because the novelization was released six months before the movie, many people mistakenly believed that the film was based on Asimov's book. Its modern and imaginative production design received five nominations at the 39th Academy Awards mostly in technical departments, winning for Best Visual Effects and Best Art Direction in Color.

The movie used the concept of miniaturization in science fiction along with The Incredible Shrinking Man and inspired an animated television series of the same name.