Margaret Nixon McEathron (February 22, 1930 – July 24, 2016), known professionally as Marni Nixon, was an American soprano and playback singer for featured actresses in movie musicals. She was best known for dubbing the singing voices of the leading actresses in films, including The King and I, West Side Story, and My Fair Lady.

Besides her voice work in films, Nixon's varied career included some film roles of her own, television, opera, musicals on Broadway and elsewhere throughout the United States, concerts with major symphony orchestras, and recordings.

Nixon's first onscreen appearance was as Sister Sophia in the 1965 film 'The Sound of Music'. In the DVD commentary to the film, director Robert Wise comments that audiences were finally able to see the woman whose voice they knew so well.

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