The Axis Powers is a term for the alliance of Germany, Italy, Japan, and the other countries allied to them during World War II. The three major Axis powers referred to themselves as the Rome-Berlin-Tokyo axis. The Axis powers were opposed by the Allies.
Italy, facing opposition to its war in Abysinnia from the League of Nations, forged an alliance with Germany, which had withdrawn from the League in 1933. The term was first used by Benito Mussolini, in November 1936, when he spoke of a Rome-Berlinaxis in reference to the treaty of friendship signed between Italy and Germany on October 25, 1936. The two countries would form an "axis" around which the other states of Europe could revolve. Later, in May 1939, this relationship transformed into an alliance, dubbed the "Pact of Steel".
Yugoslavia joined on March 25, 1941, but a British-supported coup d'état two days later put Yugoslavia's participation in question (although King Peter II of Yugoslavia actually declared his adherence to the treaty), leading to a German occupation of Yugoslavia in April.
On April 10, 1941, the Independent State of Croatia was proclaimed on parts of Yugoslav territory, ruled by the Ustaše; with the leader of the state being Ante Pavelić. Other parts of Yugoslavia were either annexed, governed directly by the coalition forces, or by other locals (e.g. general Milan Nedić).
Following the successful invasion of France by German forces and the capture of Paris, France surrendered to Germany on the 24 June 1940. Germany divided France into occupied and non-occupied zones with the latter following under the leadership of the Vichy government, which was the official government of France led by prime minister Henri Philippe Pétain. The occupation collimated into two Frances. Charles de Gaulle directed forces called the Free French Forces in exile.
Manchukuo, meaning Manchuria, was a puppet state set up by Japan on February 18, 1932. The country's independence was not recognized by the League of Nations causing Japan’s to withdraw. Italy, Germany and the Chinese Nationalist Government under Wang Jingwei were the only major nations to recognize it. Manchuria met its dissolution in 1945 following Japan's defeat ending World War II.
In Allied usage, Finland was often referred to as an Axis country, but it was never a signatory. Finland characterized its relationship with Germany during the Continuation War as co-belligerence.
The Italian name Roberto briefly acquired a new meaning from "Roma-Berlin-Tokio" during this time.
The Axis of Evil named by George W. Bush has the same connotations behind it as the Axis Powers, although the countries named are not allied with each other.