Clifford Charles Devlin Thorburn CM (born 16 January 1948) is a Canadian retired professional snooker player. Nicknamed "The Grinder" because of his slow, determined style of play, he won the World Snooker Championship in 1980, defeating Alex Higgins 18–16 in the final to become the first world champion in snooker's modern era from outside the United Kingdom. He remains the sport's only world champion from the Americas. He was runner-up in two other world championships, losing 21–25 to John Spencer in the 1977 final and 6–18 to Steve Davis in the 1983 final. Ranked world number one during the 1981–82 season, he was the first non-British player to top the world rankings.

In 1983, Thorburn became the first player to make a maximum break in a World Championship match, achieving the feat in his second-round encounter with Terry Griffiths. He won the invitational Masters in 1983, 1985, and 1986, making him the first player to win the Masters three times and the first to retain the title. He retired from the main professional tour in 1996. Inducted into Canada's Sports Hall of Fame in 2001 and the Snooker Hall of Fame in 2014, he competed in Snooker Legends events and on the World Seniors Tour, winning the 2018 Seniors Masters at the Crucible Theatre at age 70. He retired from competitive snooker after the 2022 UK Seniors Championship

Thorburn was born on 16 January 1948 in Victoria, British Columbia. His parents separated when he was eighteen months old.: 104  He was abandoned by his mother, and after spending about two years in an orphanage during a custody dispute, was raised by his father and his paternal grandmother. He was told that his mother had died, but, aged twenty, learnt that she was still alive.

He played pool and lacrosse in his youth, and set a one-game scoring record of ten goals in the Greater Victoria Minor Lacrosse Association "midget division" in 1958. He left school at the age of 16, and travelled across Canada playing pool and snooker money matches, taking jobs as a dishwasher and working on a garbage truck to help earn money for his stakes. In 1968 he entered his first tournaments, and won the Toronto City Championship. He spent time with Fred Davis and Rex Williams when they toured Canada in 1970, and afterwards became a resident professional at the House of Champions club in Toronto.In July 1970, he reportedly made a maximum break of 147 in a non-competitive game against Fred Hardwick. He made six century breaks in winning the North American championship in 1971, equalling the record, jointly held by Joe Davis and George Chenier, for most century breaks in a single tournament.