Billie Jean King beats Bobby Riggs in the Battle of the Sexes tennis match at the Houston Astrodome.

In tennis, "Battle of the Sexes" describes various exhibition matches played between a man and a woman, or a doubles match between two men and two women in one case. The term is most famously used for an internationally televised match in 1973 held at the Houston Astrodome between 55-year-old Bobby Riggs and 29-year-old Billie Jean King, which King won in three sets. The match was viewed by an estimated fifty million people in the United States and ninety million worldwide. King's win is considered a milestone in public acceptance of women's tennis.

Two other matches commonly referred to as a "battle of the sexes" include one held four months earlier in 1973 between Riggs and Margaret Court over the best of three sets, and one in 1992 between Jimmy Connors and Martina Navratilova over the best of three sets, with hybrid rules favoring the female player dubbed "The Battle of Champions". These matches were won by Riggs and Connors, respectively.

At least eight other exhibition matches have been played between notable male and female tennis players starting in 1888, though only some of them were referred to at the time as a "battle of the sexes".

Billie Jean King (née Moffitt; born November 22, 1943) is an American former world No. 1 tennis player. King won 39 Grand Slam titles: 12 in singles, 16 in women's doubles, and 11 in mixed doubles. She often represented the United States in the Federation Cup and the Wightman Cup. She was a member of the victorious United States team in seven Federation Cups and nine Wightman Cups. For three years, she was the United States' captain in the Federation Cup.

King is an advocate for gender equality and has long been a pioneer for equality and social justice. In 1973, at age 29, she won the "Battle of the Sexes" tennis match against the 55-year-old Bobby Riggs. She was also the founder of the Women's Tennis Association and the Women's Sports Foundation. She was also instrumental in persuading cigarette brand Virginia Slims to sponsor women's tennis in the 1970s and went on to serve on the board of their parent company Philip Morris in the 2000s.

Regarded by many in the sport as one of the greatest women's tennis players of all time, King was inducted into the International Tennis Hall of Fame in 1987. The Fed Cup Award of Excellence was bestowed on her in 2010. In 1972, she was the joint winner, with John Wooden, of the Sports Illustrated Sportsman of the Year award and was one of the Time Persons of the Year in 1975. She has also received the Presidential Medal of Freedom and the Sunday Times Sportswoman of the Year lifetime achievement award. She was inducted into the National Women's Hall of Fame in 1990, and in 2006, the USTA National Tennis Center in New York City was renamed the USTA Billie Jean King National Tennis Center. In 2018, she won the BBC Sports Personality of the Year Lifetime Achievement Award.

Standing at only 1.64 m (5 ft 4+1⁄2 in), King is the shortest player to have ever won a grand slam in tennis.