Martina Hingis (born September 30, 1980 in Košice, Czechoslovakia) is a retired professional tennis player who spent a total of 209 weeks as World No. 1. She won five Grand Slam singles titles (three Australian Opens, one Wimbledon, and one US Open). She also won nine Grand Slam women's doubles titles, winning a calendar year doubles Grand Slam in 1998, and one Grand Slam mixed doubles title.

Hingis set a series of "youngest-ever" records before ligament injuries in both ankles forced her to withdraw temporarily from professional tennis in 2002 at the age of 22. After several surgeries and long recuperations, Hingis returned to the WTA tour in 2006. She then climbed to world number 6 and won three singles titles. On November 1, 2007, Hingis announced her retirement from tennis while admitting she had tested positive for cocaine during Wimbledon in 2007. She denied using the drug. On January 4, 2008, she was banned from tennis for two years after both cocaine tests (samples A and B) turned positive. She has stated that she will not return to professional tennis when this ban expires. She participated in the seventh (2009) series of the BBC's Strictly Come Dancing, partnering Matthew Cutler, where she was the first contestant to be voted out.

Hingis was born to accomplished tennis players: a Czech mother, Melanie Molitorova, and a Hungarian father living in Košice (Slovakia), Károly Hingis. Molitorova was a professional tennis player, who was once ranked tenth among women in Czechoslovakia, and was determined to develop Hingis into a top player as early as pregnancy. Her father was ranked as high as nineteenth in the Czechoslovakian tennis rankings. She was named after tennis legend Martina Navratilova. Hingis's parents divorced when she was six, and she and her mother relocated around a year later to Trübbach in Switzerland. Her father, who continued to live in Košice as a tennis coach, said in 1997 that he had seen little of his daughter after the split.