Daniel Jeffery Henderson (born August 24, 1970) is an American former mixed martial artist and Olympic wrestler, who last competed as a middleweight in the Ultimate Fighting Championship.
 He was the last Strikeforce Light Heavyweight Champion and was the last Welterweight (80 kg ) and Middleweight (95 kg ) champion of Pride Fighting Championships.
 Additionally, Henderson was the Brazil Open '97 Tournament Champion, the UFC 17 Middleweight Tournament Champion, the Rings: King of Kings 1999 Tournament Champion and the Pride Weltwerweight Grand Prix Tournament Champion.
 During his career, Henderson also challenged for the UFC Middleweight Championship (2x), the UFC Light Heavyweight Championship and the Strikeforce Middleweight Championship.
 He was the first mixed martial artist to concurrently hold two titles in two different weight classes in a major MMA promotion.
 At the time of his retirement after UFC 204, he was the oldest fighter on the UFC roster.
 Known to be one of the greatest mixed martial artists of all time having defeated a total of seventeen MMA world champions across four major MMA promotions (UFC, PRIDE FC, Strikeforce, and RINGS).
Michael Bisping ( , ; born 28 February 1979) is an English mixed martial artist and actor.
 He fights in the Ultimate Fighting Championship (UFC), and is the current UFC Middleweight Champion.
 He is a former Cage Rage Light Heavyweight Champion, and "The Ultimate Fighter 3" Light Heavyweight Tournament winner.
 At UFC 78, he became the first English fighter in a UFC main event and at UFC 199, he became the first English fighter to win a UFC championship.
Randall "Randy" Duane Couture ( ; born June 22, 1963) is an American actor, retired United States Army Sergeant, retired mixed martial artist and former collegiate and Greco-Roman wrestler.
 During his tenures in the Ultimate Fighting Championship (UFC), Couture became a three-time UFC Heavyweight Champion, two-time UFC Light Heavyweight Champion, an interim UFC Light Heavyweight Champion and the UFC 13 Heavyweight Tournament Winner.
 Couture is the first of only three fighters to hold two UFC championship titles in two different divisions (along with B.J. Penn and Conor McGregor).
Carla Kristen Esparza (born October 10, 1987) is an American professional mixed martial artist who competes in the Strawweight division of the Ultimate Fighting Championship (UFC).
 Largely known for her grappling abilities, Esparza was the first UFC Strawweight Champion, the first Invicta FC Strawweight Champion, and was generally considered the best strawweight fighter in the world while holding each title.
 She earned the UFC championship by winning a 16-woman tournament that was televised on the reality series "The Ultimate Fighter".
 She also competed in Bellator MMA's first women's tournament.
Jens Johnnie Pulver (born December 6, 1974) is an American professional mixed martial artist and undefeated boxer and kickboxer.
 Pulver was the inaugural UFC Lightweight Champion in addition to serving as the head coach on "The Ultimate Fighter 5" reality show against long-time rival B.J. Penn.
 In mixed martial arts, Pulver competed at the Lightweight, Featherweight, Bantamweight and Flyweight divisions in addition to competing at the Middleweight, Light Middleweight, and Welterweight divisions as a professional boxer.
 While perhaps best known for competing in the UFC, Pulver has also competed in Pride Fighting Championships, for the PRIDE 2005 Lightweight Grand Prix.
 He is to-date the youngest UFC Lightweight Champion in the UFC history, eventually relinquishing his title, after two defenses, due to a contract dispute.
 Pulver officially retired from combat sports in 2014.
 Pulver is considered the founder of the UFC lightweight division.
Patrick "Pat" Healy (born July 20, 1983) is an American professional mixed martial artist currently competing in the Lightweight division of Titan FC.
 A professional competitor since 2001, Healy has also formerly competed for the UFC, Strikeforce, the WEC, the IFL, the MFC, King of the Cage, ACB and Shark Fights.
 His twin brother, Ryan, is also a professional mixed martial artist.
Miesha Theresa Tate ( ; born August 18, 1986) is an American Mixed Martial Arts Pundit and former mixed martial artist who competed in the Ultimate Fighting Championship (UFC) and is a former UFC Women's Bantamweight Champion.
 Primarily known for her grappling ability, Tate became a wrestler while attending Franklin Pierce High School in Tacoma, Washington and won a state championship during her senior year in 2005.
 She began her professional mixed martial arts (MMA) career in 2007, and won the bantamweight championship of the Freestyle Cage Fighting promotion in 2009.
 Tate gained increased recognition in 2011, when she won the Strikeforce Women's Bantamweight Championship.
 She has also won a silver medal in the FILA Grappling Championships.
Conor Anthony McGregor (Irish: "Conchúr Antóin Mac Gréagóir" ; born 14 July 1988) is an Irish professional mixed martial artist and professional boxer who is currently signed to the Ultimate Fighting Championship (UFC).
 He is the reigning UFC Lightweight Champion, and former UFC Featherweight Champion.
 During his mixed martial arts (MMA) career, McGregor has competed as a featherweight, lightweight, and welterweight.
 As of 2017, McGregor is ranked 2nd on UFC's pound for pound rankings.
Sean Keith Sherk (born August 5, 1973) is a retired American mixed martial artist and former UFC Lightweight Champion.
 Sherk competed in the Ultimate Fighting Championship and was one of the first combatants to have been a championship competitor in multiple weight divisions (having also competed for the UFC Welterweight Championship).
 He was the second UFC Lightweight Champion in the organization's history after Jens Pulver vacated his title 5 years earlier.
 Sherk also spent time competing in the Japan-based organizations, PRIDE Fighting Championships and Pancrase; going undefeated in both promotions.
 He holds one of the longest undefeated streaks in mixed martial arts history, with only four career losses, all to fellow-UFC Champions.
 Sherk announced his official retirement from mixed martial arts competition in September 2013 having last fought three years prior.
Jay Dee "B.J." Penn (born December 13, 1978) is an American professional mixed martial artist and Brazilian Jiu-Jitsu practitioner.
 Penn debuted and competed in the Ultimate Fighting Championship (UFC), and later in K-1.
 Prior to fighting for the UFC, he became the first American Gold medalist of the World Jiu-Jitsu Championship.
 In mixed martial arts, Penn has competed in the Featherweight, Lightweight, Welterweight, and Middleweight divisions.
 As a former UFC Lightweight Champion and UFC Welterweight Champion, he is one of only three fighters in UFC history to win titles in multiple weight classes.
 Penn was also a Co-champion in the UFC 41 Lightweight Tournament, due to an eventual draw opposite Caol Uno in the tournament finale.
 Through his tenures as champion, Penn unofficially unified the UFC Lightweight Championship (against Sean Sherk) and broke the all-time lightweight title defense record.
 Penn was inducted into the UFC Hall of Fame, as the inaugural inductee in the Modern-Era Wing by career-long rival Matt Hughes, during "International Fight Week" in July 2015.

Question: Who is the first Irish professional mixed martial artist to hold two UFC championship titles in two different divisions?
Answer: Conor McGregor