I've probably seen her face before, but I don't recall it.
Well, actually, I definitely had, just that I didn't know it:
After My Fair Lady was released in 1964, Nixon appeared onscreen in only one movie — The Sound of Music — as Sister Sophia, one of the nuns who sing "How Do You Solve a
Problem like Maria?" The film's star — Julie Andrews — didn't need any help in the singing department.