Mary Tyrone is a fictional character from the play "Long Day's Journey Into Night," written by Eugene O'Neill. She is the matriarch of the Tyrone family, struggling with her past and the impact of her husband's career as an actor. Throughout the play, Mary battles her addiction to morphine, which complicates her relationships with her husband, James Tyrone, and their sons, Jamie and Edmund. Her character represents themes of illness, denial, and the search for solace in a troubled family dynamic.