Born Angela Maxine O'Brien on January 15, 1937 in San Diego, California. Her film debut was one-minute shot in MGM's Babes on Broadway. Her big moment came when she was cast in Journey for Margaret. This film shot her into instant stardom and also resulted in Angela changing her name to Margaret. Throughout the 1940s Margaret was a major child star. Her unforgettable performance as "Tootie" in Vincente Minnelli's Meet Me in St. Louis won her an Academy Award as "Outstanding Child Actress" of her day. She gave brilliant performances in such films as The Canterville Ghost, Our Vines Have Tender Grapes, The Secret Garden and Little Women. By the early 1950s Margaret had made a mint for MGM and earned a personal fortune. But like most other child stars, she failed in her bid to graduate into adolescent roles and in 1951 she retired from the screen. She remained active on TV and on the dinner-theater circuit. In 1979 she began a stint as a civilian aide for Southern California to Secretary of the Army Clifford Alexander.
Received the Women's International Center (WIC) Living Legacy Award in 1996. So skillful but natural was this young actress that when called upon by a certain director to gush some tears, she quite innocently asked: "When I cry, do you want the tears to run all the way down, or should I stop them halfway down?" In a practice common among child actors at the time, O'Brien adopted as her professional first name the she name of the character who was her first credited part in Journey for Margaret. Her special Academy Award as Outstanding Juvenile Performer for Meet Me in St. Louis was stolen and she was unable to regain it for nearly fifty years when two antique collectors came across it in an antique shop and managed to give it back to O'Brien. Gave birth to her only child, daughter Mara Tolene Thorsen, in 1977. In 1959, Ms. O'Brien starred in a national stage tour of "The Young And The Beautiful" by author Sally Benson (creator of the book that became O'Brien's most famous film, Meet Me in St. Louis). Co-starring opposite O'Brien in the stage play of "The Young And The Beautiful" was Dirk Wayne Summers, who later became an award winning writer and director in films and television. Measurements: 33-21-34 (at age 18), (Source: Celebrity Sleuth magazine) In April 2006, O'Brien was presented with one of the first two Lifetime Achievement Awards ever awarded by the SunDeis Film Festival at Brandeis University. (Celeste Holm received the other.)