I seem to be in love with eponyms. There's something fascinating about people whose lives in fame (or infamy) help enrich a language. Today's word is a commonization of the last name of Vidkun Quisling (1887-1945), a Norwegian fascist politician who helped German Nazi forces to occupy Norway during World War II. Thereafter, he was made the head of the puppet government. After Germany's loss in the war, he was tried and convicted of high treason and executed.
The term quisling for traitors was coined by the British newspaper, The Times, in 1940 when they titled an article "Quislings everywhere". The word means traitor not only in English but in several European languages. Something like a modern-day Judas???
Trivia: In a wartime Norwegian cartoon, "Audience with Hitler, Quisling says: "I am Quisling", and Hitler replies: "And the name?".
Sources: www.yourdictionary.com, answers.com, Wikipedia
Images: Google: Quisling with Hitler