Brock Lesnar
No single fighter has had as great an impact on the sport of MMA than Brock Lesnar. Before he was picked up by the UFC, Lesnar was famous as a pro-wrestler in World Wrestling Entertainment (WWE), where his freakishly muscly physique helped make him a household name.
It was no surprise that headlines and shockwaves were made when it was announced that he had signed a deal with the UFC back in late-2007. Lesnar’s UFC career was initially successful for both himself and the company. He won the Heavyweight title in his fourth ever MMA fight before he defended it against Mir and Shane Carwin.
Lesnar’s win over Carwin was especially special given that he had recovered from diverticulitis (a digestive disease) prior to the bout. In 2011, Lesnar once again came down with diverticulitis and had another operation to address the problem.
He only returned to the UFC once after that in a first round loss against Alistair Overeem, immediately after which Lesnar announced his retirement. Few, if any, MMA fighters were able to be so dominant in the first five fights of their careers, which will always beg the question of whether Lesnar could have been one of the best ever had he not come down with diverticulitis.