Billie Jean King (née Moffitt; born November 22, 1943) is a former professional tennis player from the United States. She won 12 Grand Slam singles titles, 16 Grand Slam women's doubles titles, and 11 Grand Slam mixed doubles titles. King has been an advocate against sexism in sports and society. She won "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 owner of World Team Tennis, which was founded by her former husband, Larry King, Dennis Murphy, Frank Barman, and Jordan Kaiser.
Billie Jean Moffitt was born in Long Beach, California, 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.