Adolf Hitler (1889-1945), German political and military leader and one of the 20th century's most powerful dictators. Hitler converted Germany into a fully militarized society and launched World War II in 1939. He made anti-Semitism a keystone of his propaganda and policies and built the Nazi Party into a mass movement. He hoped to conquer the entire world, and for a time dominated most of Europe and much of North Africa. He instituted sterilization and euthanasia measures to enforce his idea of racial purity among German people and caused the slaughter of millions of Jews, Sinti and Roma (Gypsies), Slavic peoples, and many others, all of whom he considered inferior.