Lanny King McDonald (born February 16, 1953) is a Canadian former professional ice hockey player who played for the Toronto Maple Leafs, Colorado Rockies and Calgary Flames during his 16-year career in the National Hockey League (NHL). He played over 1,100 games in the NHL between 1973 and 1989 in which he scored 500 goals and over 1,000 points. His total of 66 goals in 1982–83 remains the Flames' franchise record for a single season.

McDonald was selected by the Maple Leafs as the fourth overall pick in the 1973 NHL Amateur Draft and established himself as an offensive forward with three consecutive 40-goal seasons in Toronto in the mid-1970s. His trade to the Rockies in 1979 resulted in Toronto fans protesting the deal in front of Maple Leaf Gardens. He played parts of three seasons in Denver, before he was sent to Calgary in 1981 where he spent the remainder of his career. He co-captained the Flames to a Stanley Cup championship in his final season of 1988–89.

McDonald is among the most popular players in Flames history and his personality and bushy red moustache made him an iconic figure within the sport. McDonald won the Bill Masterton Memorial Trophy for dedication and sportsmanship in 1983 and in 1988 was named the inaugural winner of the King Clancy Memorial Trophy for his leadership and humanitarian presence, in particular through his long association with the Special Olympics.

Internationally, McDonald represented Team Canada as a player on two occasions and in a management role three times. His assist created the tournament winning overtime goal of the inaugural 1976 Canada Cup, and he was director of player personnel of Canada's 2004 World Championship winning team.

The Flames retired McDonald's uniform number 9 in 1990. McDonald was inducted into the Hockey Hall of Fame in 1992, the Alberta Sports Hall of Fame in 1993 and Canada's Sports Hall of Fame in 2017. In 2015, he was named chairman of the board of the Hockey Hall of Fame, after serving nine years on the Hall's selection committee. He was named to the Order of Hockey in Canada in 2022, and has been a trustee of the Stanley Cup since 2023.

McDonald was born February 16, 1953, in Hanna, Alberta. He is the youngest of four children after brother Lynn and sisters Donna and Dixie. His father, Lorne, tended the family farm near the hamlet of Craigmyle, 35 kilometres (22 mi) outside Hanna. The young Lanny viewed his father as his hero, often following Lorne around helping with whatever chores he could. McDonald credits his father for teaching him the value of honesty and hard work. His mother, Phyllis, was a full-time teacher who was frequently involved with community events.

Learning to skate at the age of five, McDonald immediately developed a passion for hockey. He served as a stick boy, helping manage equipment, for his father's community team and grew up listening to the famous Foster Hewitt radio broadcasts of Hockey Night in Canada. McDonald shared his father's passion for the Toronto Maple Leafs; he was given his middle name, King, after Maple Leafs' star King Clancy. He began playing organized hockey at the age of six and, despite both having full-time commitments, his parents drove him and Lynn to Hanna for their practices and games. McDonald recalled that half of his time in youth hockey was spent in Hanna, and the other half in the car. He completed high school while playing in Lethbridge, choosing to remain with his junior A team in 1970–71 rather than join the Medicine Hat Tigers of the Western Canada Hockey League (WCHL) so that he could complete his diploma.

McDonald began his junior career in 1969 with the Lethbridge Sugar Kings of the tier II Alberta Junior Hockey League (AJHL). He appeared in 34 games for the Sugar Kings as a 16-year-old, scoring two goals. The following season, 1970–71, he emerged as a leading scorer, recording 37 goals and 82 points in 45 games. He was voted the league's most valuable player and named to the second All-Star team. Additionally, McDonald appeared in six WCHL games with the Calgary Centennials.