Martina Navratilova

Europe has produced many a women's tennis champion over the past 60 years, but none has challenged orthodoxy quite as vigorously as Martina Navratilova, both on and off the court. She was the left-hander with a serve-and-volley game in a world dominated by right-handers who preferred to stick to the baseline.

She burst onto the international scene as a lone European taking on American champions like Chris Evert, but by the time she bowed out of professional singles' tournaments, after an unmatched 168 singles titles, she was the lone American taking on Europeans such as Steffi Graf. She incurred the fury of then communist authorities in her home country of Czechoslovakia by defecting to the U.S. in 1975, and made waves in her adopted home by talking openly about her bisexuality soon after becoming a U.S. citizen in 1981. Love her or hate her — and few remained indifferent — Navratilova was the dominant force in women's tennis in the 1980s.

Alongside her record nine singles titles at Wimbledon, six of them in consecutive years, she imbued women's tennis with a powerful new look and feel that will endure. "Martina revolutionized the game by her superb athleticism and aggressiveness, not to mention her outspokenness and her candor. She brought athleticism to a whole new level," Evert said when Navratilova officially retired from singles tournaments in 1994.

Born in 1956 in Prague, she took the name of her stepfather, Marislav Navratil, and began hitting tennis balls as a young child. She was a Czech champion by 15, and turned professional a year later. She once described Wimbledon as being like "a drug. Once you win it for the first time you feel you've just got to do it again and again and again." And she did: her first singles victory there came in 1978, when she defeated Evert to reach the world No. 1 spot, and her last came 12 years later in 1990.

She continued to play doubles and won her last Wimbledon mixed doubles title in 2003, at age 46. "I hope, when I stop, people will think that somehow I mattered," she once said. There's no doubt that they will.