Who: Greg Louganis
Olympics: Seoul 1988

Ouch to the hundredth power. After hitting the board attempting a two-and-one-half pike, Louganis had a concussion and every person who watched it got a real bad case of the squeamies. We're not assholes for putting this on here because of how amazingly he recovered. Despite the obvious fail and pain, Louganis rebounded to win the gold medals in the 3-meter and 10-meter diving competitions for the second straight Olympics.