Serena Williams is widely regarded to be one of the greatest tennis players of all time. She has won 23 Grand Slam singles titles, the most by any player in the Open Era. The Women’s Tennis Association (WTA) ranked her world No. 1 in singles on eight separate occasions between 2002 and 2017. Williams holds the most Grand Slam titles in singles, doubles, and mixed doubles combined among active players. Her 39 Grand Slam titles put her joint-third on the all-time list and second in the Open Era: 23 in singles, 14 in women’s doubles, and two in mixed doubles. She is the most recent female player to have held all four Grand Slam singles titles simultaneously (2002–03 and 2014–15) and the third player to achieve this twice, after Rod Laver and Graf. Williams has won 14 Grand Slam doubles titles, all with her sister Venus. Williams is also a five-time winner of the WTA Tour Championships in the singles division. She 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.