Esther Mary Vergeer (born 18 July 1981, Woerden) is a Dutch wheelchair tennis player. Vergeer has not lost a match in singles since February 2003. She has won 39 Grand Slam titles, five Paralympic Gold Medals and 21 Masters titles. Vergeer has been the world number one since 1999. Vergeer is also a former wheelchair basketball player. She was part of the team which won the European Championships in 1997.