Samantha "Sam" Jane Stosur (/ˈstoʊzər/ STOH-zər; born 30 March 1984) is an Australian professional tennis player, well known for her powerful serve, which is among the best in women's tennis. She is a former World No. 1 in doubles.
Stosur has won a total of five Grand Slam titles to date; one in singles at the 2011 U.S. Open; two in women's doubles; and two in mixed doubles. She was also a finalist at the singles event at the 2010 French Open.