#4 Martina Navratilova
One of the greatest tennis stars to have played the sport, Martina Navratilova, retired from the sport in 1994 with 18 Grand Slam singles titles and 31 doubles titles. However, she shocked the world when she announced her return to tennis in 2000.
While she did not achieve success in singles, she found a lot of success in doubles and mixed doubles, winning the Australian Open and Wimbledon mixed doubles crown in 2003. She finally retired from the sport in 2006 after winning the mixed doubles event in 2006.
#3 Martina Hingis
Martina Hingis broke numerous records as a youngster, including being the youngest ever player to win a Grand Slam title. However, due to injuries, she retired at the age of 22. She made a return in 2006 but was banned for two years for the use of cocaine and due to another injury as well.
She made a return to the sport once again in 2013 and decided to focus on doubles and mixed doubles. She found plenty of success, becoming the world no. 1 doubles player for a long time and notching up numerous Grand Slam titles, especially with India's Sania Mirza and Leander Paes.