Floyd Joy Mayweather Jr. (born Floyd Joy Sinclair; February 24, 1977) is an American professional boxer and promoter. Widely considered to be one of the greatest boxers of all time, undefeated as a professional, and a five-division world champion, Mayweather has won fifteen world titles and the lineal championship in four different weight classes (twice at welterweight). As an amateur he won a bronze medal in the featherweight division at the 1996 Olympics, three U.S. Golden Gloves titles (at light flyweight, flyweight, and featherweight), and the U.S. national title at featherweight.
Conor Anthony McGregor (born 14 July 1988) is an Irish professional mixed martial artist who is currently signed to the Ultimate Fighting Championship (UFC). He is the reigning UFC Lightweight Champion, and former UFC Featherweight Champion. During his career, McGregor has competed as a featherweight, lightweight, and welterweight. In 2008, McGregor started his mixed martial arts (MMA) career and, in 2012, he won both the Cage Warriors Featherweight and Lightweight Championships, holding both titles concurrently before vacating them to sign with the UFC. In 2015, at UFC 194, McGregor defeated José Aldo for the UFC Featherweight Championship via knockout thirteen seconds into the first round. This was the fastest victory in UFC title fight history. Upon defeating Eddie Alvarez for the UFC Lightweight Championship at UFC 205, McGregor became the first fighter in UFC history to hold titles in two weight divisions simultaneously.