The "Big Three" leaders who attended the World War II conferences were:
- Franklin D. Roosevelt - The President of the United States.
- Winston Churchill - The Prime Minister of the United Kingdom.
- Joseph Stalin - The leader of the Soviet Union.
These leaders met at several important conferences during the war to discuss military strategy, post-war reconstruction, and the future of Europe, including conferences such as the Tehran Conference (1943), the Yalta Conference (1945), and the Potsdam Conference (1945).