Floyd Mayweather pulled the plug on his career after scoring a definitive win over Oscar De La Hoya in May 2007, citing there was nothing left for him to prove. By the end of the year, though, Mayweather had changed his mind, returning to knock out Ricky Hatton that December. Following that fight, Mayweather again said he was done and again returned, this time nearly two years later to defeat Juan Manuel Marquez in September 2009. Money Mayweather has been fighting steadily since. Not to mention, he's still undefeated!
(Photos from left: GABRIEL BOUYS/AFP/Getty Images, Eric Jamison/Getty Images)