In political jargon, useful idiot is a term for people perceived as propagandists for a cause whose goals they are not fully aware of, and who are used cynically by the leaders of the cause.
In Russian language, the equivalent term "useful fools" (полезные дураки) was in use at least in 1941. 
The term has been used in a similar sense as fellow travellers and other Communism or Soviet Union sympathizers in Western countries during the Cold War. The implication was that, although the people in question naïvely thought of themselves as standing for a benign socialist ideological cause, and as valued allies of the Soviet Union, they were actually held in contempt and were being cynically used by the Communist Party of Soviet Union for subversive activities in their native Western countries. The use of the term in political discourse has since been extended to other propagandists, especially those who are seen to unwittingly support a malignant cause which they naïvely believe to be a force for good.
A New York Times article from 1948, on contemporary Italian politics, documented usage of the term in an article from the social-democratic Italian paper L'Umanita. The French equivalent, "idiots utiles", was used in a newspaper article title in 1946.
A similar term, useful innocents, appears in Austrian-American economist Ludwig von Mises's "Planned Chaos" (1947). Von Mises claims the term was used by communists for liberals that von Mises describes as "confused and misguided sympathizers". The term useful innocents also appears in a Readers Digest article (1946) titled "Yugoslavia's Tragic Lesson to the World", an excerpt from a, at the time, forthcoming book (no title printed) authored by Bogdan Raditsa (Bogdan Radica), a "high ranking official of the Yugoslav Government". Raditsa says: "In the Serbo-Croat language the communists have a phrase for true democrats who consent to collaborate with them for 'democracy.' It is Korisne Budale, or Useful Innocents." Although Raditsa translates the phrase as "Useful Innocents", the word budala (plural: budale) actually translates as "fool" and synonyms thereof.
Despite often being attributed to Lenin, in 1987, Grant Harris, senior reference librarian at the Library of Congress, declared that "We have not been able to identify this phrase among [Lenin's] published works."
A 2010 BBC radio documentary titled Useful Idiots listed among "useful idiots" of Joseph Stalin several prominent British writers including H. G. Wells and Doris Lessing, the Irish writer George Bernard Shaw, the American journalist Walter Duranty, and the singer Paul Robeson.
- The expression was used, e.g., by Russian literary critic Vasily Bazanov (ru) when commenting on Nikolai Leskov's anti-nihilistic novels: "Русские «нигилисты» в руках польских агентов, судя по роману Лескова, были не больше как «полезные дураки» и глупые энтузиасты, которых можно заставить итти в огонь и в воду" ("According to Leskov's novel, Russian 'nihilists' were for Polish agents no more than useful fools and silly enthusiasts, which could be goaded to go through fire and water."), citing from Bazanov's monograph "Из литературной полемики 60-х годов", Petrozavodsk, 1941 p. 80 The phrase refers to a contemporary opinion that Russian revolutionary movement (colloquially called "nihilists") was a result of anti-Russian agitation by the Polish insurgents.
- "Useful Idiots", a documentary, BBC World Service, Last updated: 7 july, 2010 (Retrieved March 22, 2011)
- "COMMUNIST SHIFT IS SEEN IN EUROPE; Tour of Two Italian Leaders Behind Iron Curtain Held to Doom Popular Fronts", Arnold Cortesi, New York Times, June 21, 1948 p. 14
- [full citation needed]
- "PLANNED CHAOS" p.17 in electronic document; Ludwig von Mises;http://mises.org/books/plannedchaos.pdf
- "Reader's Digest Service" article titled "Yugoslavia's Tragic Lesson to the World"; p.138 in electronic document; Bogdan Radista;http://books.google.com/books?id=rCgYAQAAIAAJ&q=%22koristne+Budale%22&dq=%22koristne+Budale%22&hl=en&sa=X&ei=akPWT7WVO6ag2gWl452OCw&ved=0CDUQ6AEwAA
- An editorial clarification of a quotation in the article "Ходорковский просит Лондон не идти на сделки с Кремлем", BBC, Russian Service
- Mona Charen, Useful Idiots: How Liberals Got It Wrong in the Cold War and Still Blame America First, 2003, ISBN 0895261391
- Paul Kengor, Dupes: How America's Adversaries Have Manipulated Progressives for a Century, 2010, ISBN 1-935191-75-6
- William Safire on the term
- Boller, Jr., Paul F.; George, John (1989). They Never Said It: A Book of Fake Quotes, Misquotes, and Misleading Attributions. New York: Oxford University Press. ISBN 0-19-505541-1.
- Useful Idiots - Part One