27. Elena Dementieva:
Russian tennis star Dementieva was on top of the proverbial tennis world after storming to a silver medal in singles at the 200 Olympic Games. She followed that up with a gold medal in the same event at the 2008 Olympic Games.
Dementieva went on to win 16 WTA singles titles. She also made the 2004 French Open finals and the 2004 US Open finals. In 2009, she reached her peak in terms of world ranking at No. 3. Despite all of this success, however, Dementieva grew tired of the endless grind of professional sports. She announced her retirement at only 29 years old following a loss in the 2010 WTA Championships. She later married and had a child. To this day, she’s considered one of the greatest female tennis players to have never hoisted a Grand Slam Trophy. Perhaps that could have changed if she played well into her 30s.