Marni Nixon, known as Hollywood’s “invisible* voice,” has died aged 86.

    The singer appeared, uncredited*, on many of the biggest movie musicals of all time — dubbing* the voices for Deborah Kerr in “The King and I,” and Audrey Hepburn in “My Fair Lady.”

    She also sang the high notes for Marilyn Monroe in “Diamonds Are a Girl’s Best Friend” and “ghosted” Natalie Wood’s vocals on “West Side Story.”

    Nixon died of breast cancer on Sunday, her agent confirmed to the BBC.

    For most of her career, the classically trained musician remained unknown. Twentieth Century Fox made her sign a contract saying she would never reveal the ghost-singing on “The King and I.” The story only came out later, when Kerr herself credited Nixon’s work in a press interview.

    The clandestine* nature of her work led Time magazine to dub* Nixon “the ghostess with the mostest.”

    The singer likened her work to that of a stuntman*, and collaborated closely with the stars to perfect the screen illusion.

    Kerr “wanted to look like she was really singing,” Nixon told the Washington Post, “and wanted to be using the same muscles and the same stretches you do in expressions.”

    Hepburn even gave Nixon a lift to the set of “My Fair Lady” every morning; and they worked together to ensure their performances matched.

    In later years, Nixon appeared as a soloist* with the New York Philharmonic, performed on Broadway and in opera houses and hosted the Emmy Award-winning children’s television show “Boomerang.”

    She also taught at the California Institute of the Arts, and toured for many years with Liberace.

    Nixon first had breast cancer in 1985, and wrote in her autobiography* of the trauma* of appearing on Broadway as chemotherapy* caused her hair to fall out when the disease returned in 2000.

    (SD-Agencies)