Tatum Beatrice O'Neal (born November 5, 1963) is an American actress best known for her film work as a child actress in the 1970s. She is the youngest to win a competitive Academy Award, at the age of 10, which she won for her performance as Addie Loggins in Paper Moon (1973) opposite her father Ryan O'Neal. She then starred in The Bad News Bears in 1976, followed by Nickelodeon (1976), International Velvet (1978) and Little Darlings (1980).

In 1986, she married tennis player John McEnroe, with whom she had three children. The couple separated in 1992 and were divorced in 1994.

O'Neal was born in Los Angeles, California, the daughter of actors Ryan O'Neal and Joanna Moore, who had appeared in various motion pictures and television shows. Her brother, Griffin, was born in 1964. In 1967, her parents divorced and her father quickly remarried. Her father's marriage to actress Leigh Taylor-Young produced Tatum's half-brother, Patrick, but the union ended in divorce in 1973. Tatum has another half-brother, Redmond, from Ryan O'Neal's relationship with actress Farrah Fawcett. O'Neal's mother died in 1997 of lung cancer at age 63, after a career in which she had appeared in such movies as Walk on the Wild Side and Follow That Dream.