The infamous leader who led the Soviet Union during World War II is Joseph Stalin. Holding power from the mid-1920s until his death in 1953, Stalin implemented policies that had significant effects on the USSR and its role in the war. His leadership included a ruthless consolidation of power, forced collectivization, and the Great Purge. During World War II, Stalin played a crucial role in the defeat of Nazi Germany, especially through the Soviet Union's enormous sacrifices and victories at battles such as Stalingrad.