Bethanie Lynn Mattek-Sands (née Mattek; born March 23, 1985) is an American professional tennis player. She is an Olympic Gold medalist in mixed doubles, has won five Grand Slam titles in women's doubles and two in mixed doubles.

Mattek has won five singles and three doubles titles on the ITF Women's Circuit, and her best results in singles on the WTA Tour to date are reaching the semifinals of the tournaments in Cincinnati, in 2005 and Birmingham, in 2008 and the final of the Bell Challenge in 2008 and 2010. In women's doubles, she has won 26 WTA Tour titles, most notably the 2015 Australian Open, 2015 French Open, 2016 US Open, 2017 Australian Open and 2017 French Open, all with Czech partner Lucie Šafářová. In mixed doubles, she won the 2012 Australian Open and the 2015 French Open and a gold medal at the 2016 Rio Olympics. Mattek also played World TeamTennis for the Hartford FoxForce in 2000, the Sacramento Capitals in 2006, and the New York Sportimes in 2008.