“It’s a Wonderful Life” (the 1946 film) was directed by Frank Capra and the final screenplay is officially credited to Frances Goodrich, Albert Hackett, and Frank Capra, with additional (uncredited) work by writers like Jo Swerling and others.

The movie is based on the short story/novella “The Greatest Gift,” which was written by Philip Van Doren Stern, whose tale about a man shown what the world would be like if he had never been born became the core narrative that Capra and his screenwriters adapted into the film.