It was donated by the Governor General of Canada Lord Stanley of Preston in 1892, and is the oldest professional sports trophy in North America.
After a series of league mergers and folds, it became the de facto championship trophy of the NHL in 1926, though it was nominally still subject to external challenge.
The origins of the Challenge era come from the method of play of the Amateur Hockey Association of Canada prior to 1893.
In 1912, Cup trustees declared that it was only to be defended at the end of the champion team's regular season.
As a compromise, the trustees decided that if the Montreal HC won the challenge match, the Victorias would become the Stanley Cup champions.
^ C. The January 31 (a Saturday) game was tied 2–2 at midnight and the Mayor of Westmount refused to allow play to continue on Sunday.
[18][19] Several days after the Victoria Aristocrats – Toronto Hockey Club series, Stanley Cup trustee William Foran wrote to NHA president Emmett Quinn that the trustees are "perfectly satisfied to allow the representatives of the three pro leagues (NHA, PCHA, and Maritime) to make all arrangements each season as to the series of matches to be played for the Cup."
[21] In 1919, the Spanish influenza epidemic forced the Montreal Canadiens and the Seattle Metropolitans to cancel their series tied at 2–2–1, marking the first time the Stanley Cup was not awarded.
[25] The format for the Stanley Cup championship changed in 1922, with the creation of the Western Canada Hockey League (WCHL).
Other leagues and clubs have issued challenges, but from that year forward no non-NHL team has played for it, leading it to become the de facto championship trophy of the NHL.
[30][31] A 2006 Ontario Superior Court case found that the trustees had gone against Lord Stanley's conditions in the 1947 agreement.
[31] Since 1927, the league's playoff format, deciding which teams advanced to the Stanley Cup Finals, has changed multiple times.
In 2021, the COVID-19 pandemic and the resulting travel restrictions along the Canada–United States border forced the league to temporarily realign the teams into four regional divisions with no conferences, and hold a divisional-based playoff format: the four divisional playoff champions advanced to the Stanley Cup Semifinals, and the winners of those series moved on to the Finals.
The following 16 teams unsuccessfully challenged for a Stanley Cup only once: Berlin Dutchmen (1910), Dawson City Nuggets (1905), Halifax Crescents (1900), Moncton Victorias (1912), Montreal Canadiens (1914), New Glasgow Cubs (1906), Ottawa Capitals (1897), Ottawa Victorias (1908), Port Arthur Bearcats (1911), Smiths Falls (1906), Sydney Millionaires (1913), Toronto Marlboros (1904), Toronto Professionals (1908), Toronto Wellingtons (1902), Victoria Aristocrats (1914), Winnipeg Rowing Club (1904).
Unless marked otherwise, teams played in the NHL exclusively at the time they competed for the Stanley Cup.