Women's Tennis. Lots of examples there. And a fair few examples of the demands that top level sport put on still developing adolescent bodies leading to injury-enforced early departures from the sport.
Probably the biggest one was Justine Henin retiring, aged 25, when ranked World No.1. Even more shocking was the timing, mid-season, a few weeks prior to her favourite tournament, the French Open, which she had won for the previous three years straight, and four times in the preceding five. I don't think she has ever said exactly why this retirement happened, and rightly no-one can compel her to do so. A combination of injury, stress of the job and problems in her personal life are the best guess. Came back, but never hit the same heights and is now retire again through injury.
Thinking of Henin inevitable leads to Kim Clijsters, who initially retired aged 24. That retirement was long planned with the intention of having a child and a normal life, though injury brought it forward by a few months.
Came back, but a bit itinerantly, although that is mostly atributable to injury. Though arguably some of these injuries (ankle hurt dancing at a wedding, anyone?) are caused by tennis not being persued with a monkish devotion but instead trying to fit that in with some halfway typical family life. Which just makes her all the more likeable in my view.
Martina Hingis, retired at 22 as a result of a combined succession of injuries and loss of motivation. Later reversed but the comeback was terminated by a failed drugs test. Still only 31 yeards old, but now gone for good.
Anna Kournikova, injuries and other interests seeing her out of the professional game by 2003, age 22. Her active playing days feel like a generation ago, but she is still only 30!
Andrea Jaeger, out of the sport at 19 through injury.
Tracy Austin, done as a major force by her early twenties and retired through injury in her mid twenties.