The genocide of the Jews would have not been possible without:

Civil service bureaucracy: collected and stored information about Jews
Police forces in Germany and German-occupied territories: many victims were taken by the police rather than the Gestapo or SS
The SS: Adolf Eichmann developed a system for transporting Jews to the death camps; SS Death's Head battalions and Einsatzgruppen carried out killings
The Wehrmacht (German armed forces)
Industry: companies like Volkswagen and Mercedes had their own slave labour camps; IG Farben the chemical giant developed the gas used to kill Jews in concentration camps
The German people: anti-Semitism was widespread; many Germans took part in some aspect of the Holocaust, even if they did not support mass killing