Male Tennis Grand Slam winners

She is known for "The Battle of the Sexes" in 1973, in which she defeated Bobby Riggs, a former Wimbledon men's singles champion.

King is the founder of the Women's Tennis Association, the Women's Sports Foundation, and World Team Tennis, which she founded with her former husband, Lawrence King.

Billie Jean Moffitt was born into a conservative Methodist family, the daughter of a fireman father and housewife mother. Her younger brother Randy Moffitt grew up to become a professional baseball player, pitching for 12 years in the major leagues for the San Francisco Giants, Houston Astros, and Toronto Blue Jays.

Billie Jean attended Long Beach Polytechnic High School.[5] After graduating, she attended California State University, Los Angeles (CSULA) because her parents could not afford Stanford or the University of Southern California (USC).

She married Lawrence King in Long Beach, California on September 17, 1965. In 1971, she had an abortion, revealed to the public in a Ms. Magazine article in 1972 by Lawrence without consulting Billie Jean in advance. King said in her 1982 autobiography that she decided to have an abortion because she believed her marriage was not solid enough to bring a child into her family. Billie Jean and Lawrence divorced in 1987.

By 1968, King realized that she was interested in women, and in 1971, King began an intimate relationship with her secretary, Marilyn Barnett. King acknowledged the relationship when it became public in a May 1981 "palimony" lawsuit filed by Barnett, making King the first prominent professional female athlete to come out as a lesbian. King said that she had wanted to retire from competitive tennis in 1981 but could not afford to because of the lawsuit.

"Within 24 hours [of the lawsuit being filed], I lost all my endorsements; I lost everything. I lost $2 million [$4, 784, 141 in current dollar terms] at least, because I had longtime contracts. I had to play just to pay for the lawyers. In three months I went through $500, 000 [$1, 196, 035 in current dollar terms]. I was in shock. I didn't make $2 million in my lifetime, so it's all relative to what you make." King said in 1998 that Martina Navratilova was not supportive when King was outed, resulting in their relationship having a "very bad five years."

King learned to professionally play tennis on the public courts of Long Beach, California. She was an aggressive, hard-hitting net-rusher, with excellent speed. Chris Evert, however, said about King, "Her weakness is her impatience."