Quisling is a term used in Scandinavian languages and in English to mean a citizen or politician of an occupied country who collaborates with an enemy occupying force – or more generally as a synonym for traitor or collaborator. The word originates from the surname of the Norwegian war-time leader Vidkun Quisling, who headed a domestic Nazi collaborationist regime during World War II.

Vidkun Abraham Lauritz Jonssøn Quisling was a Norwegian military officer, politician and Nazi collaborator who nominally headed the government of Norway during the country's occupation by Nazi Germany during World War II.