Which NHL team was the first to come back from a 3-0 series deficit to win the Stanley Cup?

The Toronto Maple Leafs were the first NHL team to overcome a 3–0 series deficit and win the Stanley Cup, defeating the Detroit Red Wings in the 1942 Final.

Detroit won the first three games, putting Toronto on the brink of elimination. The Maple Leafs then won four straight, taking the best-of-seven series 4–3. The comeback is commonly called a reverse sweep and remains the only time a team has won a Stanley Cup Final after falling behind 3–0.

Toronto’s turnaround began with a 4–3 victory in Game 4. The Maple Leafs then shut out Detroit 3–0 in Game 5, won Game 6 by the same score, and completed the comeback with a 3–1 victory in Game 7 at Maple Leaf Gardens.

The 1942 Final was also the first Stanley Cup Final to reach a seventh game. Toronto captain Syl Apps received the Cup from NHL president Frank Calder after the deciding victory.