Clarence Henry "Happy" Day (June 1, 1901 – February 17, 1990), later known as Hap Day, was a Canadian professional hockey player who played 14 seasons in the National Hockey League for the Toronto Maple Leafs and New York Americans. Day enjoyed a 33-year career as a player, referee, coach and general manager, and was inducted into the Hockey Hall of Fame in 1961.
In 1927, the St. Pats were purchased by Conn Smythe and renamed the Toronto Maple Leafs. Smythe kept Day as team captain. He also became a partner in Smythe's sand and gravel business. After Smythe acquired star defenceman King Clancy from the Ottawa Senators in 1931, Day and Clancy formed one of the top defence pairings in the NHL. The team won the Stanley Cup in 1932. While still playing for the Leafs, Day became coach of the West Toronto Nationals OHA junior team and led them to a Memorial Cup victory in 1936. On September 23 1937, Day was sold to the New York Americans and spent one season there before retiring as a player in 1938. His 11-year tenure as captain of the St. Pats/Maple Leafs is second only to George Armstrong, though Mats Sundin will likely pass him with the start of the 2008-09 NHL season.
Day worked as a referee for the next two years before returning to the Leafs as coach. He guided the team through the 1940s, winning the Stanley Cup five times in 10 seasons. He is still the second-winningest coach in Leafs history.
Smythe promoted Day to assistant general manager in 1950. His name was engraved on the cup a 7th time in 1951. In 1955, Smythe gave Day control over most hockey operations, but remained general manager on paper. Just after the Leafs were eliminated in the playoffs in March 1957, Day was publicly embarrassed by Smythe, who told the media that he didn't know if Day was available to return to the Leafs for the following season. Officially, Day resigned, but behind the scenes he had been pushed out and was replaced by a committee headed by Smythe's son Stafford Smythe.
Day retired to enter business life, running Elgin Handles in St. Thomas, Ontario until selling it to his son in 1977. Day was almost convinced by Jack Kent Cooke to become the first general manager of the Los Angeles Kings in 1967, but he decided not to take the job, recommending Larry Regan instead.