When Natalie Wood was seen in the movie West Side Story, it wasn't she who was singing "Tonight" or "I Feel Pretty." Neither was it Audrey Hepburn who really sang "I Could Have Danced All Night" or "Wouldn't It Be Lover-ly" when she appeared in My Fair Lady. And Deborah Kerr never sang "An Affair to Remember" in the movie of the same name, or "Getting to Know You" in The King and I. For all those actresses, the voice that actually sang the songs was that of Marni Nixon. Marni also sang part of "Diamonds Are A Girl's Best Friend" for Marilyn Monroe in Gentlemen Prefer Blondes.