Floyd Landis

This American cyclist was an unlikely successor to the grand Lance Armstrong dynasty at the Tour de France. However, he somehow managed to win the arduous three-week race quite comfortably. Questions were raised almost immediately after Landis' surprise win. He was promptly tested and it was found that his urine sample contained exceptionally high amounts of testosterone. 

Like most athletes, Landis tried to blame it on everyone but himself. Alas, his pleas of innocence were in vain and he was stripped of his title and banned from cycling for two years. However, he did come clean about his drug usage in 2010.