"Moon River" was written for the film Breakfast at Tiffany's. Audrey Hepburn sings the song in the movie, but Henry Mancini's orchestral version is just as well known. Audrey Hepburn's version of the song was not available to the general public on a recording until after her death in 1993.
Henry Mancini won an amazing 20 Grammy Awards in his long career including 5 for the music from Breakfast at Tiffany's alone.