Serena Williams is the younger sister of Venus Williams.
Serena Williams . 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 . Venus Ebony Starr Williams ( born June 17 , 1980 ) is an American professional tennis player who is generally regarded as one of the all-time greats of women 's tennis and who , along with younger sister Serena Williams , is credited with ushering in a new era of power and athleticism on the women 's professional tennis tour .