Name the leader of the Soviet Union during World War II.

Joseph Stalin was the leader of the Soviet Union during World War II, playing a crucial role in the conflict. He rose to prominence following the death of Vladimir Lenin in 1924 and became the General Secretary of the Communist Party, consolidating power through a series of purges and political maneuvers. Under Stalin's leadership, the Soviet Union initially signed the Molotov-Ribbentrop Pact with Nazi Germany in 1939, which allowed for a temporary non-aggression agreement between the two powers. However, after Germany invaded the Soviet Union in 1941, Stalin became a key figure in the Allied forces' resistance against Axis powers.

Stalin's leadership was characterized by intense military strategy, rapid industrialization, and significant human cost due to his policies, which included widespread purges and famines. His decisions were pivotal in major battles like the Battle of Stalingrad, which marked a turning point in the war. Following the war, Stalin continued to influence global politics as the Soviet Union solidified its status as a superpower. Understanding his role during this pivotal era is essential for grasping the complexities of World War II and the subsequent Cold War period.