Larry Wall's answer provides the core information. But Jim Thorpe was an inspiration to me in childhood, so I want to add a bit more. Most importantly, the International Olympic Committee reversed its decision and re-instated Jim Thorpe's amateur status and Olympic medals in 1983.
Jim Thorpe, 1/2 Native American and 1/2 European in ancestry, was a man who broke through racial barriers in sports, much as Jackie Robinson did a generation later as the first black man in professional baseball.
Jim Thorpe was rated "the Greatest Athlete of the 20th Century" in an ABC poll of sports fans. His gold medals in the Pentathlon (5 sports) and Decathlon (10 sports) with scores that held top seat for 20 years, plus a professional career that included baseball, football, and basketball clearly make him a most unusual athlete in his versatility.
You can learn more at http://en.wikipedia.org/wiki/Jim_Thorpe