Conor McGregor is by far and away the biggest star to ever step foot inside the Octagon.
In 2013, the Irishman made his promotional debut against Marcus Brimage at UFC on Fuel TV 9. At the time, McGregor was a highly touted prospect out of the UK-based Cage Warriors promotion, but nobody could have guessed just how far his star would rise over the next three years. Following his sensational 13-second knockout of Jose Aldo at UFC 194, he was officially off to the races. McGregor quickly became one of the biggest names in the sport, leading him to legendary matchups with Nate Diaz, Eddie Alvarez, and Khabib Nurmagomedov.