World map of countries that fought in World War II: The Allies are in green (those in light green entered after the attack on Pearl Harbor), the Axis are in blue, and neutral countries are in grey.

The Allied Powers (or Allies of World War II) were a group of nations that fought against the Axis countries in World War II. They were successful in defeating the Axis nations. The war ended in 1946. The group of nations was later named the United Nations by U.S. President Franklin Roosevelt. The main great powers, sometimes called "The Big Three", were the United Kingdom, the United States, and the Soviet Union.

The Big Three:

• United Kingdom (from September 1939)
•  Soviet Union (from June 1941)
•  United States (from December 1941)