Una O'Connor (1880 - 1959) was an Irish-American actress.

She also appeared in supporting roles in various stage productions and achieved an outstanding success in the role of Janet McKenzie, the nearly deaf housemaid, in Agatha Christie's Witness for the Prosecution at Henry Miller's Theatre on Broadway from 1954–56; she also appeared in the film version in 1957, directed by Billy Wilder. As one of the witnesses, in what was essentially a serious drama, O'Connor's character was intended to provide comic relief. It was her final film performance.

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