Punishment: Disqualified from race
Honestly, while we can't condone cheating, what Rosie Ruiz pulled off at the 1980 Boston Marathon was one of the more incredible feats in recent memory. These were the days before the police escorts and video monitoring of the course, which enabled Ruiz to ride the T all the way to a half mile from the finish line before she popped onto the course and seemingly "won" the race. While it didn't take long for her ruse to be discovered, Ruiz had (however briefly) set the women's record for fastest marathon time ever.
45. Rosie Ruiz jumps to the last mile to win the Boston Marathon.