Hitler and Stalin emerged as dictators of Nazi Germany and the Soviet Union, respectively, in the same era. Stalin assumed power over the Soviet Union in the mid-1920s, while Hitler and his Nazi Party controlled Germany by 1933. Their regimes spanned World War II, in which the two dictators were main antagonists. Stalin, victorious in that conflict, lived until 1953. The main similarities between the two dictators lie in the methods they employed to rule. Both men used terror and mass propaganda in an attempt to control the lives of their people. They violently purged their own parties, including political allies, in an effort to consolidate power. Stalin's purges in 1934 cost hundreds of thousands of lives, and Hitler's so-called "Night of the Long Knives," among other brutal purges, killed many party members, including long-time supporters. Both leaders operated concentration and forced labor camps for perceived opponents of the state, and both used secret police to establish an atmosphere of fear and suspicion necessary to sustain their rule.

Despite these similarities, Stalin and Hitler were diametrically opposed in an ideological sense. Stalin had risen to power as a consequence of the Bolshevik Revolution, in the wake of Lenin. He went about modernizing the Soviet state through collective agriculture and state-run industries. He was, in short, a communist. Hitler had risen to power in no small part due to fears of communism, especially among German businessmen. While he definitely expanded the powers of the German state, he did not embark on the kind of collectivist program that Stalin did, because it was anathema to National Socialism. Stalin's ideology was fundamentally based upon class struggle, arguing that the world (and the Soviet state) was threatened by capitalists that had to be resisted. Likewise, he framed Soviet unity as a function of this class struggle. Hitler infamously viewed the world in radicalized terms, scapegoating Jews (who he often publicly associated with Bolshevism and socialism) in particular. German identity and unity was radicalized, with Hitler framing the nation as the expression of pure "Aryan" civilization.