An autarky is an economy that does no trade with the outside world, or an ecosystem not affected by influences from its outside, and relies entirely on its own resources. In the economic meaning, it is also referred to as a "closed economy."

The word "autarky" is from the Greek αὐτάρκεια, which means "self-sufficiency" (derived from αὐτο, "self," and ἀρκέω, "to suffice"). It is sometimes confused with autarchy (Greek: αὐταρχία), which either means self-government or government by absolute rule. ("Autarchy" is sometimes also used as a variant spelling of "autarky").

Today, economical autarkies are found very rarely. An example of a current autarky is North Korea, based on the government ideology of Juche (self-reliance). However, even North Korea has a small amount of trade between China and Japan.

In the past, fascism imposed autarky in Italy after an embargo sanctioned by the League of Nations. Autarky was a primary goal for Adolf Hitler in his aggression in Europe, capturing arable land in Poland to provide for Germany's principal import, food. The first heading of the Hitler's infamous Hossbach Memorandum was "Autarky."

After the victory of Francisco Franco's Nationalist forces in the Spanish Civil War, Spain was embargoed by the Allies; this led to a form of autarky in Spain, symbolized by the Biscúter automobile.