Martina Navratilova

The Czech-American left-hander who defected to the United States in 1975 and dominated women's tennis for nearly two decades, Martina Navratilova won 18 Grand Slam singles titles and a record 31 Grand Slam doubles titles -- 59 Grand Slams in total across all disciplines. Her fitness revolution (the first female player to train with weights year-round) redefined the physical standards of the women's game and she continued competing in doubles events until age 49.