Title: Mark Allen (footballer)
Content:  Mark Stephen Allen (born 18 December 1963) is an English former professional footballer who played as a striker. In 1984, Allen had a spell with second-level side Pallo-Iirot in Finland.
Title: Mark Allen (triathlete)
Content:   Mark Allen (born January 12, 1958 in Glendale, California) is an American triathlete and six-time Ironman Triathlon World Champion.
Title: Mark Allen (snooker player)
Content:  Mark Allen (born 22 February 1986) is a Northern Irish professional snooker player from Antrim. He won the World Amateur Championship in 2004, turned professional the following year, and took only three seasons to reach the top 16. In his fourth professional season, he beat the defending champion Ronnie O’Sullivan en route to the semi-finals of the 2009 World Championship, where he lost to the eventual winner John Higgins. Allen reached his first ranking event final at the 2011 UK Championship, losing to Judd Trump. He won his first ranking title the following year at the 2012 World Open. He has won six ranking titles to date, most recently the 2021 Northern Ireland Open. He captured his first Triple Crown title at the 2018 Masters. A prolific break-builder, Allen has compiled more than 500 century breaks in professional competition. He has made two maximum breaks, achieving his first in the 2016 UK Championship and his second in the 2021 Northern Ireland Open qualifying round.
Title: Mark Allen (snooker player)
Content:  Allen's most notable achievement during the 2020/2021 season was winning the 2020 Champion of Champions. He defeated Ronnie O'Sullivan in a contentious quarter-final that saw O'Sullivan accusing Allen of deliberately standing in his line of sight and Allen accusing O'Sullivan of being a 'bully'. Allen went on to defeat Judd Trump in the semi-finals and Neil Robertson 10–6 in the final.
Title: Mark Allen (triathlete)
Content: DNC - Did not compete ; DNF - Did not finish 
Title: Mark Allen (snooker player)
Content:  At a young age, Allen considered a career in football, having trials with Sheffield Wednesday and Nottingham Forest before concentrating on snooker. Playing out of the Fountain Club in Antrim, he was Northern Ireland U14 champion in 2000, the U16 champion in 2001, before winning the Irish U16, U18 and U19 titles in one weekend in 2002, becoming the first player to win all three tournaments. By the age of 16 he had recorded his first maximum break and was a winner of the Golden Waistcoat, a tournament for the best U19 players from around the world. He began his professional career by playing Challenge Tour in 2003, at the time the second-level professional tour. Before entering the 
Title: Mark Allen (triathlete)
Content:  He graduated from UC San Diego, where he was an All-American swimmer, with a degree in biology.
Title: Mark Allen (snooker player)
Content:  In the 2021/2022 season, Allen won his first Northern Ireland Open title, coming from 6–8 behind in the final to defeat John Higgins 9–8. Earlier in the tournament, in his qualifying round match against Si Jiahui, he made the second maximum break of his professional career.
Title: Mark Allen (triathlete)
Content:  the Year six times by Triathlete magazine, and in 1997 Outside magazine dubbed him The World's Fittest Man. Allen was inducted into the Ironman Triathlon Hall of Fame in 1997. He has also been inducted into the USAT Hall of Fame and the ITU Hall of Fame. Allen has summarized his career in four characters: "1-6-21-infinity". "1" is for his victory in the first official triathlon World Championship. "6" is for the six times he won the Ironman. 21 stands for his two season run of 21 straight victories, along the way defeating every one of the top 50 triathletes in the world. "Infinity" represents his acknowledgement by ESPN as "The Greatest Endurance Athlete of All Time." Allen owns and operates Mark Allen Coaching, a global online triathlon coaching concern.
Title: Mark Allen (snooker player)
Content:  Although Mark didn't succeed in the final of International championship in previous season, this time he did. In the final, he met with Neil Robertson and beat him comfortably 10-5 and also made a highest break (146). But after this triumph followed a few unsatisfactory results. Despite of them, Mark reached UK championship final after a won decider in semi-final against Stuart Bingham at the start of December. His opponent was a defending champion Ronnie O'Sullivan, who won over Allen 10-6. Just after UK championship Allen added his 5th ranking victory by winning last tournament in year 2018 Scottish open by defeating Shaun Murphy in the final. But in the second half of the season, Mark wasn't able to get further than semi-final. Allen suffered a failure in World championship, because he lost in first round against Zhou Yuelong. Despite the negative outcomes, he won more than one ranking tournament in his career for the first time and reached his highest ranking, fifth, in March 2019.

Question: What sport does Mark Allen play?
Answer: triathlon.