Martina Navratilova
Navratilova set the bar for a successful tennis career for women. She has been the only player in history to hold the No. 1 spot in both singles and doubles for more than 200 weeks. She is still regarded as one of the best female tennis players of all time, despite her retirement.
Serena Williams
Williams is also another all-time tennis great, with records to rival those of Steffi Graf. Between 2002 and 2013, she was the No. 1 singles artist six times.