Dublin-born Sara Allgood embarked upon her acting career in her native Ireland, commencing with the esteemed Abbey Theatre. Subsequently, she traversed to the English stage, where she performed for numerous years prior to making her film debut in 1918. Her warm, open Irish visage enabled her to spend a considerable amount of time portraying Irish mothers, landladies, neighborhood gossips, and similar characters.
Notwithstanding, she is most notably remembered for her portrayal of Mrs. Morgan, the mother of a family of Welsh miners, in the film How Green Was My Valley (1941),for which she garnered a nomination for the Academy Award for Best Supporting Actress. Her sister, Maire O'Neill, was also an actress in Ireland, and the celebrated Irish poet William Butler Yeats was a family acquaintance.