Of course, Jews. Hitler regarded them as the main culprits for the economic crisis in Germany before the war, and developed special hatred for them, as well as the methods of their systematic killing. Although the Holocaust victims were other nations, like Gypsies. Interestingly, Hitler officially regarded homosexuality as a disease and thought that in order to raise "higher" race, homosexuals along with other "lower" races, according to that theory, were not able to survive the struggle for survival, a large number of his associates were just homosexuals.
It is estimated that around six million Jews are killed during the war in Europe.
