The most popular UFC fighter is undoubtedly Conor McGregor. The Irish fighter, who is considered one of the greatest mixed martial artists of all time, is one of the biggest draws in UFC history. With his outspoken personality and bombastic fighting style, McGregor brought attention to the sport and helped it to become more popular around the world. His two-division title victories made him the first ever fighter to hold two championships simultaneously and cemented his place as one of the stars of the sport.