Ex-husband John McEnroe won custody of their children after a prolonged custody battle.
Daughter of actors Ryan O'Neal and Joanna Moore.
Older sister of actor Griffin O'Neal. Also the older half-sister of sportscaster Patrick O'Neal from her father's second marriage (to Leigh Taylor-Young) and Redmond O'Neal from her father's relationship with Farrah Fawcett.
Youngest person to ever win a competitive Oscar (Best Supporting Actress, Paper Moon (1973))
Disapproved of her father actor Ryan O'Neal's relationship with Farrah Fawcett.
Highest paid child star in history when she made The Bad News Bears (1976) in 1976.
Michael Jackson claimed she was his first girlfriend and by all accounts his first big love. Tatum denies this in her autobiography, saying all that happened was that he briefly kissed her without permission when she was 12 and he was 17.
Recently published her memoirs, "A Paper Life", that exposes her troubled childhood, long battles with her father and Farrah Fawcett, her sexual encounters with Melanie Griffith, Jean-Claude Van Damme and Prince Albert of Monaco, her explosive union with John McEnroe and the bitter custody suit over her three children with the tennis great. 
Her memoirs "A Paper Life" debuted at #4 on the New York Times Bestseller List.
She was named Female Star of the Year by the National Association of Theater Owners in 1976
According to her autobiography "A Paper Life", she was not named after her paternal grandmother as was widely rumored for years but actually named after jazz pianist Art Tatum.
Was voted #14 on VH1's The Greatest: 100 Greatest Kid Stars (2005).
Was cast as Blythe Hunter in Wicked Wicked Games (2006) when original choice, Sean Young, was fired following apparent clashes with the show's producers.
One of a very few performers to win an Oscar for their debut performance.
Her mother, Joanna Moore died on November 22, 1997 of lung cancer.
Granddaughter of Patricia O'Neal and Charles O'Neal.
Niece of Kevin O'Neal.
Was extremely vocal about being voted off of Dancing with the Stars (2005) before the disastrous Master P.
Disapproved of her father Ryan O'Neal's relationship with Ursula Andress so much so that she would speak about it to the tabloids even though she was just a child. However, in her 2004 memoir "A Paper Life", she wrote fondly of her, calling her kind and gentle, taking care of her when she was hurt.
Friendly with Jennifer Blanc-Biehn and Michael Biehn.
Was scheduled to appear as host on NBC's Saturday Night Live (1975) for the November 27, 1976 episode, but she was replaced at the last minute by Jodie Foster.
Turned down the role of Deborah Gelly for Sergio Leone's final movie Once Upon a Time in America (1984). Elizabeth McGovern got the part.
Was turned down by James Cameron for the role of Sarah Connor in The Terminator (1984). Linda Hamilton ended up playing the part.
Was the second choice to play Violet in Pretty Baby (1978), along with Jodie Foster. However, neither Foster nor O'Neal were among the finalists; Brooke Shields won the part.
Her former friend Michael Jackson and her father's longtime partner Farrah Fawcett died on the same day, June 25th 2009.
Gave birth to her 1st child at age 22, a son Kevin John McEnroe on May 23, 1986. Child's father is her ex-husband, John McEnroe.
Gave birth to her 2nd child at age 23, a son Sean Timothy McEnroe on September 23, 1987. Child's father is her ex-husband, John McEnroe.
Gave birth to her 3rd child at age 27, a daughter Emily Katherine McEnroe on May 10, 1991. Child's father is her ex-husband, John McEnroe.
Release of her autobiography, "A Paper Life". 
As an adult, she studied acting under Sandra Seacat, who also coached Harvey Keitel, Marlo Thomas, Isabella Rossellini, Michelle Pfeiffer, Meg Ryan, and Chris Pine.
Was the 74th actress to receive an Academy Award; she won the Best Supporting Actress Oscar for Paper Moon (1973) at The 46th Annual Academy Awards (1974) on April 2, 1974.
She was 11 years old, the same age as her character, Amanda Whurlizer, when The Bad News Bears (1976) was filmed.
Is one of 15 Oscar-winning actresses to have been born in the state of California. The others are Fay Bainter, Gloria Grahame, Jo Van Fleet, Liza Minnelli, Diane Keaton, Sally Field, Anjelica Huston, Cher, Jodie Foster, Helen Hunt, Gwyneth Paltrow, Angelina Jolie, Marcia Gay Harden and Brie Larson.