Billie Jean King was born in 1943 in California. She started playing tennis as a child on public tennis courts, and by the age of 17 (in 1961), she gained national fame as part of a team that won the women's doubles at Wimbledon.
Five years later, King won her first (of six) singles title at Wimbledon. The next year, she won the singles title at both Wimbledon and the U.S. National Championships.
As her fame grew, King became a voice for professionalism and gender equity in professional tennis, including advocating for equal prize money in men's and women's tournaments. In 1971, King became the first female athlete ever to earn more than $100,000 in prize money. When she won in the U.S. Open in 1972 and received $15,000 less payout than her male counterpart, King stated publicly that until this discrepancy was resolved, she would not continue to compete in the tournament. By the next year, the men's and women's prize pots were equal.
Perhaps King's best known accomplishment, though probably not her greatest, in 1973 King beat 55 year-old former men's professional tennis player Bobby Riggs in a showcase match. Dubbed "The Battle of the Sexes," the match brought a whole new level of public interest to women's professional tennis.
King served as the first president of the women tennis player's union, the Women's Tennis Association. She co-founded WomenSports Magazine and started the Women's Sports Foundation. When she retired from professional tennis, King had won a record 20 titles at Wimbledon, including six singles, ten women's doubles, and four mixed doubles. Her career prize money totaled over $1.5 million. In 1972, she was the first woman and first tennis player ever to be named Sports Illustrated Sportsperson of the Year.
In the 1990s, King became the coach of the U.S. Fed Cup Team and the women's Olympics tennis squad.
In her personal life, King was the first professional athlete to openly admit having a same-sex relationship. In 2001, she received an award from GLAAD for "furthering the visibility and inclusion of the community in her work."