Armando Galarraga
Galarraga’s entire legacy suffered because of one terrible mistake. He was on course for a perfect game in 2010 when he was playing for the Detroit Tigers. The umpire admitted he made a horrible error and apologized directly to Galarraga afterward (via USA Today Sports).
Even The White House attempted to intervene to change the course of history. However, MLB refused to overturn the umpire’s decision because they didn’t want to set a dangerous precedent. The state of Michigan recognized Galarraga’s perfect game even if it didn’t enter the league’s official annals.