Serena Williams plays in women's singles and doubles competitions.
Serena Williams . Williams holds the most Grand Slam titles in singles , doubles , and mixed doubles combined amongst active players . 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 ) . Her total of 23 Grand Slam singles titles marks the record for the most Grand Slam wins by a tennis player in the Open Era , and is second on the all-time list behind Margaret Court ( 24 ) . 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 .