- Note: This article is not about basis vectors or anything related to the coordinate system.
The Axis was the group of countries, all dictatorships, who were aligned against the Allied Powers (Great Britain, United States, Soviet Union and other allied countries) during World War II.
The three main countries in the Axis were:
- Germany (and Austria) under the Nazi rule of Adolf Hitler
- Italy under the Fascist rule of Benito Mussolini
- Imperial Japan under a military dictatorship (Emperor Hirohito was nominally the leader but more of a figurehead during WWII)
Other countries in the Axis included:
- Vichy France under the rule of Nazi collaborationist Philippe Pétain between 1940 and 1944
- Croatia, under the rule of Ante Pavelić and the Ustaša (close allies of Fascist Italy) between 1941 and 1945 (the rest of Yugoslavia was invaded and divided among Germany, Italy, and Bulgaria.)
- And several puppet governments set up by Germany, Italy, and Japan in occupied countries such as Thailand, Manchuria, and Albania.
 Not officially part of the Axis
Two European countries with Fascist dictatorships did not join the Axis and officially remained neutral during World War II: Spain under Francisco Franco, and Portugal under António de Oliveira Salazar. Those two countries, unlike the rest of Europe, remained under Fascist rule until the early 1970s.
Some sources also list Finland as an Axis country. This is because Finland was at war with the Soviet Union at the same time Nazi Germany was and the two countries cooperated in military activity against the USSR. However, after the USSR withdrew from Finland to concentrate on driving Nazi forces out of their country, Finland turned against the Nazis and fought to drive German troops out of their country in 1944-45.
 Usage (or more like it, mis-usage) today
A certain demagogic politician has attempted to revive the Axis term, in the context of a modern "Axis of Evil", to refer to something other than the Nazi/Fascist dictatorships of WWII and to drum up support for war in the Middle East with a Godwin's Law style. See homeland security for more on his modus operandi.