Mark Messier is a Canadian former professional ice hockey player. In 1976 Messier tried out for the junior Spruce Grove Mets of the Alberta Junior Hockey League (AJHL), where his father, Doug Messier, was coaching. As Messier was only 15 (the age limit for the league was 20), Doug did not expect him to make the team, though he surprised and was added to the roster.

He played a quarter of a century in the NHL (1979–2004) with the Edmonton Oilers, New York Rangers, and Vancouver Canucks. After his playing career he served as special assistant to the president and general manager of the Rangers. Messier is considered one of the greatest ice hockey players of all time. As of 2021, he is second on the all-time career lists for playoff points (295) and regular season games played (1756), and is third for regular season points (1887). He is a six-time Stanley Cup champion—five with the Oilers and one with the Rangers—and is the only player to captain two teams to Stanley Cup championships (record holds as of 2021). His playoff leadership while in New York, which ended a 54-year Stanley Cup drought in 1994. He twice won the Hart Memorial Trophy as the league's MVP, in 1990 and 1992, and in 1984 he won the Conn Smythe Trophy as the playoffs MVP. He is a 15-time NHL All-Star.

In 2007, he was inducted into the Hockey Hall of Fame, in his first year of eligibility. In 2017 Messier was named one of the "100 Greatest NHL Players" in history.On June 30, 2017, he was named an Officer of the Order of Canada by Governor General David Johnston for "contributions to hockey as an outstanding player."