Brock Lesnar is the only athlete in history to have won a world title in mixed martial arts, professional wrestling and collegiate wrestling. He has won seven WWE Championships, one UFC Heavyweight Championship and one NCAA Division I Heavyweight Championship; in his career he also won the WWE Universal Championship three times and the IWGP Heavyweight Championship once.
After making his main roster debut in March of 2002, he won the WWE Championship at SummerSlam against The Rock, becoming the youngest world champion in WWE history. He also won the 2002 King of the Ring and the 2003 and 2022 Royal Rumble. He left WWE in March 2004, after losing a match against Bill Goldberg at WrestleMania XX, to pursue a career in American football.
In April 2012, he returned to WWE after an eight-year absence, performing primarily as a part-timer. On April 6, 2014, at WrestleMania XXX, The Undertaker's 23-year undefeated streak at WrestleMania ended, while between April 2, 2017 and August 19, 2018, he held the Universal Championship for a reign of 503 days. On January 29, 2022 Brock Lesnar won the royal rumble match.
On November 15, 2008, at UFC 91, he defeated multiple champion Randy Couture to capture the UFC Heavyweight Championship. In October 2009, he took time off due to diverticulitis and returned on July 3, 2010, at UFC 116, where he defeated champion Shane Carwin to unify the heavyweight title. He retired from mixed martial arts in January of 2012, one month after losing a match to Alistair Overeem.
On July 9, 2016, he returned to the octagon at UFC 200, winning by unanimous decision against Mark Hunt; however, the outcome of the match was converted into a no contest due to Lesnar's positivity in the doping tests.