Billie Jean King was an athlete.
The Battle of the Sexes were three notable tennis matches between a man and a woman . Billie Jean King ( née Moffitt ; born November 22 , 1943 ) is an American former World No. 1 professional tennis player . King won 39 Grand Slam titles : 12 in singles , 16 in women 's doubles , and 11 in mixed doubles . The Grand Slam tournaments , also called majors , are the four most-important annual tennis events .