Tatum O'Neil arrested for buying drugs

She wasn't very active, but it's wrong to assume she was totally non existent.

This is from wikipedia:

In 1974, Tatum O'Neal became the youngest person ever to win an Academy Award, a record that still stands as of 2008. She won the Academy Award for Best Supporting Actress and the Golden Globe Award for New Star Of The Year - Actress for her performance in Paper Moon. O'Neal played the role of Addie Loggins, a child con artist being tutored by a Depression-era grifter played by her father, Ryan. She was 10 years old at the time she won the award.

Other movies in which O'Neal appeared include The Bad News Bears, Nickelodeon, International Velvet, and Little Darlings. She appeared as the title character in the Faerie Tale Theatre episode Goldilocks and the Three Bears. Her acting career took a backseat to her marriage to John McEnroe, the professional tennis player, for many years, but in 2005 she began a recurring role as Maggie Gavin on the firehouse drama series Rescue Me, portraying the unbalanced and lively sister of Tommy Gavin, played by Denis Leary. O'Neal's character is married to a firefighter in her brother's firehouse.

In January 2006, she participated in the second season of ABC's reality series Dancing with the Stars but was eliminated in the second round. She went on to do commentary for the series on Entertainment Tonight.

I've actually never heard of her until today.