The Geheime Feldpolizei (German: [ɡəˈhaɪmə ˈfɛltpoliˌtsaɪ] ^ⓘ; transl. "Secret Field Police"), shortened to GFP, was the secret military police of the German Wehrmacht from July 1939 until the end of the Second World War in 1945. Its units carried out plainclothes and undercover security work in the field. Their operations included clandestine operations, counterpropaganda, counterinsurgency, counterintelligence, formation of a counterinsurgency intelligence network, detection of treasonable activities, infiltration of resistance movements, gathering intelligence and destroying targets, protecting military installations, assisting the German Army (German: Heer) in courts-martial investigations, tracking and raiding targets to capture or kill, and setting-up security checkpoints in high-risk areas. GFP personnel, who were also classed as Abwehrpolizei, operated as an executive branch of the Abwehr (German armed-forces military intelligence), detecting resistance activity in Germany and in German-occupied Europe. They were known to torture and execute prisoners.

The need for a secret military police developed after the German annexation of the Sudetenland in 1938 and the occupation of Bohemia in 1939. Although SS Einsatzgruppen units originally under the command of the Sicherheitspolizei ("Security Police"; SiPo) had been used during these operations, the Oberkommando der Wehrmacht (OKW, " German High Command") felt that it needed a specialist intelligence agency with police functions – one that could operate with the military, but act like a security service to arrest potential opponents and eliminate any resistance. After studying data collected in Spain, Austria and Czechoslovakia, Generaloberst Wilhelm Keitel, commander in chief of the OKW, issued the "Dienstvorschrift für die Geheime Feldpolizei" ("Regulations for the secret field police"), and the GFP was formed on 21 July 1939.

Although officially part of the Wehrmacht, the GFP mainly recruited its personnel from the Kriminalpolizei, the criminal investigation police who had been assigned to the armed forces. They were assigned the legal status of Wehrmachtsbeamte auf Kriegsdauer ("military officials for the duration of the war") and retained the authority of other police agencies as well as of the Sicherheitsdienst (SD), the intelligence organisation of the Nazi Party. Initially the Geheime Feldpolizei were exclusively Wehrmacht security units, but in 1942 the Reich Security Main Office (RSHA) absorbed them.

GFP agents could wear either civilian clothes or uniforms in the course of their duties. GFP officials had the right to pass through any military roadblocks and to enter military buildings. They could use military signals and communications equipment, commandeer military vehicles, and procure military supplies and accommodation wherever necessary in execution of their duty. In occupied areas the GFP provided personal escort to military VIPs, assistance to state-security agencies in counter-espionage, interrogation of suspects, prevention of sabotage and the detection of enemy agents.

In practice, GFP activity depended on the region in which it operated. Work in occupied northern and western Europe differed markedly from operations conducted on the Eastern Front. In the Netherlands, Denmark and Norway, GFP actions mainly concentrated on the secret-police protection of senior Wehrmacht officers. In Belgium and France the GFP became an executive part of the civilian police services, working alongside the military authorities to combat acts of resistance, the British Special Operations Executive, and sabotage. It used terror tactics such as detentions, deportations and the execution of hostages.

Following the defeat of France in 1940, the GFP established its main headquarters at the Hôtel Bradford on the rue Saint Philippe du Roule in Paris (8ème arrondissement). Other sections for the departments of Nord and Pas de Calais were based at rue Traversière in Brussels. Despite their small numbers, the GFP constituted the "root" of the German police organ which terrorized the French people for four years of occupation.

Each GFP Gruppe consisted of a fifty-man unit until May 1942 when the entire command was restructured by SS-Brigadeführer Karl Oberg, the Higher SS and Police Leader (Höhere SS-und Polizeiführer, HSSPF) "Frankreich" (France). This reorganisation created the "Group 6/10" which contained the Kommando für Kapitalverbrechen (Capital crimes unit). It ran the infamous Balard shooting range at Issy-les-Moulineaux in the 15e arrondissement which was used to torture and execute 143 prisoners (though at the hands of the SS rather than the GFP).

The GFP oversaw the work done by the French Brigades Spéciales part of the Renseignements généraux. These units, which were part of the French police's intelligence service, specialised in tracking down so-called "internal enemies" (e.g. the French Resistance, the Comet Line that aided shot down Allied aircrews), Jews and those evading work conscription. The Special Brigades were based in room 35 of the Paris police headquarters. The Brigade Spéciale N°2 was notorious for using torture as well as leading investigations, manhunts, surveillance and interviews of suspects in Occupied France.