Ella O'Neill (born Mary Ellen Quinlan; August 13, 1857 – February 28, 1922) was the mother of playwright Eugene O'Neill and wife of actor James O'Neill.
O'Neill attended Saint Mary's College (Indiana) and later became the model for Mary Tyrone in Eugene O'Neill's final work Long Day's Journey Into Night, which tells the story of the Tyrone family, who closely resemble the members of Eugene's family. This character says the famous line, "Something I need terribly. I remember when I had it I was never lonely nor afraid. I can't have lost it forever, I would die if I thought that. Because then there would be no hope."