During World War II, the Axis Powers consisted of countries like Japan, Germany, and Italy. Germany was lead by Adolph Hitler, who rose to political power during the 1930's. His rise to power was credited to the tough economic times faced by German society after the punishments faced after World War I. Hirohito lead Japan during this time and tried to expand their power into China. Lastly, Benito Mussolini lead the Italian government into a fascist regime.
As for the Allied powers, they were lead by countries like the US and Soviet Union. Truman was President of the US (as of 1945) and Joseph Stalin was the leader of the Soviet Union.