Axis powers

Axis countries and Axis Powers was a military coalition of countries that fought together against the Allies during World War II. Benito Mussolini, Prime Minister of the Fascist Italy, announced that an October 1936 agreement had created an Italo-German "axis" around which future European events would revolve. Nazi Germany made a separate agreement with the Empire of Japan at the same time.

The three major powers were joined by several minor countries. The war ended in 1945 with the Axis powers losing and their alliances broken.

Berlin-Rome-Tokyo Axis Powers

The most important Axis countries organized the Berlin-Rome-Tokyo Axis Powers which they formalized with the Pact of Steel and Tripartite Pact. They included:

The three flags of Axis Powers: Nazi Germany, Fascist Italy until 1943, and Empire of Japan.

All three countries had authoritarian governments, which were (and still are) often referred to as fascist.

Other countries

Subsequent signatories of the Tripartite Pact

In addition to the main three countries, the less important Axis countries were:

Kingdom of Hungary, under Miklós Horthy
Kingdom of Romania, under Ion Antonescu (until Ion Antonescu got overthrown and declaring war on Germany in 1944)
Kingdom of Bulgaria, under Tsar Boris III (Until Boris III's assasination in 1943 and declaring war on Germany in 1944)

Hungary
Romania
Bulgaria

Other countries that helped the Axis without being a part of them were:

Co-belligerent states

Client states

Slovakia
Philippines (Second Republic)
Vietnam (Empire of Vietnam)
Manchukuo (Manchuria and eastern Inner Mongolia)
Reorganized National Government of China
Independent State of Croatia
Italian Social Republic (from 1943 because Nazis saved Benito.)

Controversial cases

Denmark, signed treaty of mutual non-aggression; accepted German troops.
Spain, was neutral, but gave non-military assistance.
Vichy France, agreed not to resist after Northern France was conquered. Did not resist Japanese occupation of French Indochina.