4. Alberto Del Rio
He may have earned major success in the world of pro wrestling, but Alberto Del Rio's career as a mixed martial artist was a mixed bag at best. Though he sports a decent 9-5 pro MMA record, Del Rio's MMA career is typically summed up by one defining moment-- 'the kick.' October 5, 2003, PRIDE FC, Saitama Japan. The masked (yes, Del Rio wore a mask, which was for some reason legal) Del Rio, known as Dos Caras Jr, stood across the ring from heavyweight legend Mirko CroCop. Less than a minute later, Del Rio is balled up in the corner unconscious, due to one of CroCop's signature head kicks. Del Rio would go on to lose to Kazuhiro Nakamura in his only other PRIDE FC bout four months later, before taking a three year hiatus from MMA. Upon returning three years later, Del Rio fought in South America, reaching a fair level of success, winning six fights in a row. Del Rio was TKO'd in his last bout in February 2010, and would later sign with the WWE, eliminating the possibility of him fighting again.