Serena Williams has a sibling.
Serena Williams . Her record of 39 Grand Slam titles puts her third on the all-time list and second in the open era : 23 in singles , 14 in women 's doubles , and 2 in mixed doubles . She is also the most recent player , together with her sister Venus Williams , to have held all four Grand Slam women 's doubles titles simultaneously ( 2009 -- 10 ) . She has won 14 Grand Slam doubles titles with her sister Venus , and the pair are unbeaten in Grand Slam doubles finals . Serena has also won four Olympic gold medals , one in women 's singles and three in women 's doubles -- an all-time record shared with her sister , Venus . The arrival of the Williams sisters has been credited with ushering in a new era of power and athleticism on the women 's professional tennis tour .