Margaret Court

The Australian who won 24 Grand Slam singles titles -- the most in history, including the calendar Grand Slam in 1970 -- Margaret Court dominated women's tennis before the Open Era and continued winning well into it, beating Billie Jean King in the notorious 1970 Wimbledon final after King had beaten Bobby Riggs in the Battle of the Sexes. Her 24 singles titles remain the record in any era, though they were accumulated partly before full Open Era conditions applied.