Quisling
term originating in Norway for a person who collaborates with an enemy occupying force – or more generally as a SYNONYM FOR TRAITOR
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.
The use of the name as a term for collaborators or traitors in general probably came about upon Quisling's unsuccessful coup d'état in 1940, when he attempted to seize power and make Norway cease resisting the invading Germans. The term was widely introduced to an English-speaking audience by the British newspaper The Times. It published an editorial on the 19th April 1940 titled "Quislings everywhere" , in which it was asserted that "To writers, the word Quisling is a gift from the gods. If they had been ordered to invent a new word for traitor… they could hardly have hit upon a more brilliant combination of letters.
"Quisling" was applied to some Communist figures who participated in the establishment of Communist regimes.
https://en.wikipedia.org/wiki/Quisling