The 1918–19 NHL season was the second season of the National Hockey League (NHL). While at first it was uncertain that the NHL would operate, and the possibility that National Hockey Association (NHA) would be resumed, the unfinished business of Eddie Livingstone's Toronto and Ottawa's NHA franchise, led to the NHL owners suspending the NHA again. Livingstone would attempt to overthrow the NHA management, and failing that, attempt to operate a rival league. The pre-season was filled with legal actions, deceptions and public verbal attacks. Ultimately, the NHL operated with three teams, in Montreal, Ottawa and Toronto. However, the season ended early with Toronto suspending operations, leaving Montreal and Ottawa to play off for the championship. Montreal would win the playoff and travel to Seattle for the Stanley Cup Finals. However, the championship series was not completed due to influenza infecting the whole Montreal team and causing the eventual death of Montreal's Joe Hall.

The National Hockey Association (NHA), initially the National Hockey Association of Canada Limited, was a professional ice hockey organization with teams in Ontario and Quebec, Canada. It is the direct predecessor of today's National Hockey League (NHL), and much of the business processes of the NHL today are based on the NHA. Founded in 1909 by Ambrose O'Brien, the NHA introduced 'six-man hockey' by removing the 'rover' position in 1911. During its lifetime, the league coped with competition for players with the rival Pacific Coast Hockey Association (PCHA), the enlistment of players for World War I and disagreements between owners. The disagreements between owners came to a head in 1917, when the NHA suspended operations in order to get rid of an unwanted owner, Eddie Livingstone.