Quisling

A quisling (/ˈkwɪzlɪŋ/; Norwegian pronunciation: [ˈkʋɪsˈlɪŋ]), in Norwegian, other Scandinavian languages, and English, is a person who collaborates with an enemy occupying force. The word originates from the Norwegian war-time leader Vidkun Quisling, who headed a domestic Nazi collaborationist regime during the Second World War.

The first use of the term quisling, in reference to followers of Vidkun Quisling, was made by Norwegian Labour Party politician Oscar Torp, in a 2 January 1933 newspaper interview. Further uses of the term were made by Aksel Sandemose, in a Dagbladet article in 1934, and by the newspaper Vestfold Arbeiderblad, in 1936.

J. R. R. Tolkien used the term in English in "On Fairy-Stories", a presentation given in 1939 and first printed in 1947. The term was widely introduced to an English-speaking audience by the British newspaper The Times. It published an editorial on 19 April 1940 titled, "Quislings everywhere", after the Norwegian Vidkun Quisling, who assisted Nazi Germany as it conquered his own country so that he could rule the collaborationist Norwegian government himself. The Daily Mail picked up the term four days after The Times editorial was published, that May The War Illustrated wrote of "potential Quislings" among the Dutch during the German invasion of the Netherlands, and the BBC brought the word into common use internationally.

...
Wikipedia