The Third Man is another example. Graham Greene wrote a treatment before he wrote the screenplay. The treatment, which wasn't written with publication in mind,

The Third Man is another example. Graham Greene wrote a treatment before he wrote the screenplay. The treatment, which wasn't written with publication in mind, was later published as a novella, and it differs from the film in several notable ways, because Greene and the directors changed things during the writing of the screenplay and the principal making of the film.