Twenty-four. It is the number every fan knows, and it is the right one. But it hides a more complicated story than it looks.
Three numbers
24, the official record. It includes the 1916 Cup, won in the National Hockey Association — before the National Hockey League even existed.
23, counting only the NHL era. The first came in 1924, the last in 1993.
22, counting only the seasons where the champion can be derived unambiguously from NHL playoff results. That boundary falls in 1926-27.
Why 1927 changes everything
Before that season, the NHL was not the only contender. The winner of its playoffs still had to beat a Western league champion to lift the Cup. In 1918, 1923 and 1925, the Canadiens won the NHL playoffs — and the Cup went to Toronto, Ottawa and Victoria.
Of the five pre-1927 seasons where a naive derivation names the Canadiens champion, only one matches a real Cup. One in five.
The year nobody won
In 1919 the Final pitted the Canadiens against the Seattle Metropolitans. It was abandoned after five games: the influenza pandemic had struck the Montreal side. No Cup was awarded that year — one of only two gaps in the record since 1917, along with the 2005 lockout.
And Ottawa?
The Ottawa Senators won four Cups between 1920 and 1927. They are not today's Senators: that franchise moved to St. Louis in 1934 and folded the year after. The current club was born in 1992 and has yet to win anything.
The league itself makes the distinction in its archives, where the 1927 champion is listed as “Ottawa Senators (1917)”.