The Original six is a term for the group of six teams that composed the National Hockey League (NHL) for the 25 seasons between the 1942–43 season and the 1967 NHL Expansion. These six teams are the Boston Bruins, Chicago Black Hawks, Detroit Red Wings, Montreal Canadiens, New York Rangers, and the Toronto Maple Leafs. All of the Original Six are still active franchises in the league.

The name is something of a misnomer, since there were other NHL franchises that ceased operations before 1942, including some that were founded before some of the Original Six. The term dates from the 1967 expansion which added six new franchises; hence the six expansion teams and the "Original Six". Only two of these six teams were members of the NHL in the inaugural 1917–18 season, but all six do date from the NHL's first decade, and pre-date the other 24 teams currently in the league by over forty years.

The NHL consisted of ten teams during the 1920s, but the league experienced a period of retrenchment during the Great Depression, losing the Pittsburgh Pirates, Ottawa Senators, and Montreal Maroons in succession to financial pressures. The New York Americans – one of the league's original expansion franchises, along with the Bruins and Maroons – lasted longer, but World War II provided its own economic strains and also severely depleted the league's Canadian player base, since Canada entered the war in September 1939 and many players left for military service. The Americans suspended operations in the fall of 1942, leaving the NHL with just six teams. Despite various efforts to initiate expansion after the war, including attempted restarts of the Maroons and Americans franchises, the league's membership would remain at six teams for the next twenty-five seasons.