Marni Nixon, the voice behind the stars of such films as West Side Story, The King and I and My Fair Lady, has died. She was 86. Nixon died of breast cancer Sunday in Manhattan, according to The New York Times and other media outlets.

Nixon’s film career began in the 1940s, singing the voices of the angels heard by Ingrid Bergman in Joan of Arc. She was Margaret O’Brien’s singing voice in Big City that same year  and The Secret Garden in 1949.

She went on to what would become her best-known work, the voice behind Deborah Kerr for the film version of Rodgers & Hammerstein’s The King and I, and then dubbing again for Kerr in An Affair to Remember. Her work on 1961’s West Side Story as the singing voice of Natalie Wood was kept a secret from the actress. In 1964, she worked with Audrey Hepburn performing the songs of Hepburn’s character Eliza in My Fair Lady.

Nixon’s uncredited work in the films led Time magazine to dub her “The Ghostess with the Mostest.” Her other work includes Gentleman Prefer Blondes, voicing “Diamonds Are a Girl’s Best Friend” for Marilyn Monroe.