- The United States: The US joined the war in December 1941, after the attack on Pearl Harbor, and quickly emerged as one of the war's most powerful players. The US provided vital military and financial support to its allies, and its industrial capacity was crucial to the Allied victory.
- The United Kingdom: The UK was one of the first countries to declare war on Nazi Germany in 1939, and it remained a key member of the Allied coalition throughout the war. The UK's military strength, strategic location, and global network of colonies and alliances all contributed to the Allied cause.
- The Soviet Union: The Soviet Union entered the war in June 1941, when Germany launched a surprise invasion of its territory. The Soviet Union suffered enormous losses in the war, but its vast resources and resilience eventually turned the tide against Germany. The Soviet Union's military victories on the Eastern Front were crucial to the Allied victory.
- France: France was defeated by Germany in 1940, but it remained a member of the Allied coalition through its government-in-exile in London. The French Resistance movement also played a significant role in the Allied effort, particularly during the D-Day landings in June 1944.
- China: China was involved in a long-running conflict with Japan prior to World War 2, and it remained a key ally of the Allies throughout the war. China's military resistance to Japan tied up significant Japanese forces, and it also provided intelligence and logistical support to the Allies.