Although the Jews were their primary targets, the Nazis and their collaborators also persecuted other groups for racial or ideological reasons. Among the earliest victims of Nazi discrimination in Germany were political opponents—primarily Communists, Socialists, Social Democrats, and trade union leaders. The Nazis also persecuted authors and artists whose works they considered subversive or who were Jewish, subjecting them to arrest, economic restrictions, and other forms of discrimination. The Nazis targeted Roma (Gypsies) on racial grounds. Roma were among the first to be killed in mobile gas vans at the Chelmno killing center in Poland. The Nazis also deported more than 20,000 Roma to the Auschwitz-Birkenau camp, where most of them were murdered in the gas chambers. The Nazis viewed Poles and other Slavic peoples as inferior. Poles who were considered ideologically dangerous (including intellectuals and Catholic priests) were targeted for execution. Between 1939 and 1945, at least 1.5 million Polish citizens were deported to German territory for forced labor. Hundreds of thousands were also imprisoned in Nazi concentration camps. It is estimated that the Germans killed at least 1.9 million non-Jewish Polish civilians during World War II.
During the autumn and winter of 1941-1942 in the occupied Soviet Union, German authorities conducted a racist policy of mass murder of Soviet prisoners of war: Jews, persons with "Asiatic features," and top political and military leaders were selected out and shot. Around three million others were held in makeshift camps without proper shelter, food, or medicine with the deliberate intent that they die. In Germany, the Nazis incarcerated Christian church leaders who opposed Nazism, as well as thousands of Jehovah's Witnesses who refused to salute Adolf Hitler or to serve in the German army. Through the so-called “Euthanasia Program,” the Nazis murdered an estimated 200,000 individuals with mental or physical disabilities. The Nazis also persecuted male homosexuals, whose behavior they considered a hindrance to the preservation of the German nation.