As a breast cancer survivor, she wanted to assist those who've had similar struggles and served as chairperson for the American Cancer Society, along with the March of Dimes, the Retinitis Pigmetosa Foundation and the Arthritis Foundation
Attended New York City's Professional Children's School and the Dalton School in Manhattan
A former Ford model, O'Neill was the face and spokeswoman for 30 years for Cover Girl cosmetics and is catalogued in the Smithsonian Institute's American History Museum, Center for Commercial Advertising
After her family moved from Connecticut to New York, she started her modeling career in New York City and later in Paris when she was only 15 as a means to make money to buy her own horse
Quote: "I cared very much about being a good actress, and I learned over the years․ But it wasn't my main motivating force in life․․․ I never moved to Hollywood․ I wouldn't take my clothes off to act․ Hollywood never owned me․ My need for love owned me․"
Known for her role in the 1971 film "Summer of 42," she only appeared in the film for 12 minutes
Lives on a horse farm in Nashville, Tenn․, which also serves as a ministry and retreat for girls and young women
Published her 1999 autobiography "Surviving Myself," which reveals hardships she's had to overcome in her life, from her multiple marriages to her child's drug abuse to her suicide attempt at age 14 and her subsequent move to Tennessee