The Ordnungspolizei (German: [ˈɔʁdnʊŋspoliˌtsaɪ]), abbreviated Orpo, meaning "Order Police", were the uniformed police force in Nazi Germany from 1936 to 1945. The Orpo organisation was absorbed into the Nazi monopoly on power after regional police jurisdiction was removed in favour of the central Nazi government ("Reich-ification", Verreichlichung, of the police). The Orpo was controlled nominally by the Interior Ministry, but its executive functions rested with the leadership of the SS until the end of World War II. Owing to their green uniforms, Orpo were also referred to as Grüne Polizei (green police). The force was first established as a centralised organisation uniting the municipal, city, and rural uniformed police that had been organised on a state-by-state basis.

The Ordnungspolizei encompassed virtually all of Nazi Germany's law-enforcement and emergency response organisations, including fire brigades, coast guard, and civil defence. In the prewar period, Heinrich Himmler, head of the SS, and Kurt Daluege, chief of the Order Police, cooperated in transforming the police force of the Weimar Republic into militarised formations ready to serve the regime's aims of conquest and racial annihilation. Police troops were first formed into battalion-sized formations for the invasion of Poland, where they were deployed for security and policing purposes, also taking part in executions and mass deportations. During World War II, the force had the task of policing the civilian population of the occupied and colonised countries beginning in spring 1940. Orpo's activities escalated to genocide with the invasion of the Soviet Union, Operation Barbarossa. Twenty-three Order Police battalions, formed into independent regiments or attached to Wehrmacht security divisions and Einsatzgruppen, perpetrated mass-murder in the Holocaust and were responsible for widespread crimes against humanity and genocide targeting the civilian population.