Jagdgeschwader 26 (JG 26) Schlageter was a German fighter-wing of World War II. It was named after Albert Leo Schlageter, a World War I veteran, Freikorps member, and posthumous Nazi martyr, arrested and executed by the French for sabotage in 1923. The wing fought predominantly against the Western Allies.

Formed in May 1939, JG 26 spent the Phoney War period guarding Germany's western borders following the German invasion of Poland and the outbreak of World War II. In May and June 1940 it served in the Battle of Belgium and Battle of France. From July 1940 it operated over England in the Battle of Britain under the command of Adolf Galland, future General der Jagdflieger. JG 26 remained in France and Belgium fighting against the RAF Fighter Command Circus offensive in 1941 and 1942, with considerable tactical success. In 1943 it faced the USAAF Eighth Air Force, and along with the rest of the Luftwaffe fighter force, was worn down over Western Europe combating the Combined Bomber Offensive in Defence of the Reich. In 1944, JG 26 resisted the Normandy landings and served as a "tactical" or frontline unit during Operation Market Garden and Battle of the Bulge. It continued to fight up to the unconditional surrender of Wehrmacht forces in Western Europe on 8 May 1945.

Elements of JG 26 served in other theatres. A single staffel (squadron) served in the North African Campaign and Battle of the Mediterranean. One gruppe (group) and a single staffel, fought on the Eastern Front from January to June 1943. A planned move in full to the Soviet Union did not materialise. JG 26 was well known by Allied air forces. The Royal Air Force (RAF) called the Joachim Müncheberg-led II. Gruppe the "Abbeville Boys" after their home base.

A Luftwaffe Geschwader (wing formation) was the largest homogenous flying formation. It typically was made up of three groups (gruppen). Each group contained approximately 30 to 40 aircraft in three squadrons (staffeln). A Jagdgeschwader could field 90 to 120 fighter aircraft. In some cases a wing could be given a fourth gruppe. Each wing had a Geschwaderkommodore (wing commander) supported by three Gruppenkommandeur (Group Commanders). Each squadron was commanded by a Staffelkapitän (squadron leader). The staffel contained approximately 12 to 15 aircraft. The identification in records was different depending on the type of formation. A gruppe was referred to in roman numerals, for example I./JG 26, while staffeln were described with their number (1./JG 26). The wing could be subordinated to a Fliegerkorps, Fliegerdivision or Jagddivision (Flying Corps, Division and Fighter Division) all of which were subordinated to Luftflotten (Air Fleets). The use of Fliegerdivision became redundant and the description Fliegerkorps supplanted it until the use of Jagddivision later in the war.

Jagdgeschwader 26 was one of the earliest fighter units of the Luftwaffe. Its creation began in early 1937. A plan dated 14 March 1936 by Hermann Göring, at the time Reichsminister der Luftfahrt (Minister of Aviation) and Oberbefehlshaber der Luftwaffe (Commander in Chief of the Luftwaffe), foresaw the creation of two light fighter groups in Luftkreis IV, a territorial Luftwaffe unit with its headquarters in Münster. Göring had planned for these two groups, initially organized under the designation Jagdgeschwader 234 (JG 234–234th Fighter Wing), to become operational on 1 April 1937.

I. Gruppe of JG 234 was created from the redesignation of III. Gruppe of Jagdgeschwader 134 on 15 March 1937 at Cologne Butzweilerhof Airfield. Its first commander was Hauptmann Walter Grabmann, who handed over command to Major Gotthard Handrick on 11 September 1938. The Gruppe was initially referred to I.(leichte Jäger) Gruppe and was equipped with the Heinkel He 51 B and started receiving the first Messerschmitt Bf 109 B series in May 1938. In parallel, II. Gruppe of JG 234 was formed in Düsseldorf. This Gruppe had numerous commanders during its creation phase, Major Werner Rentsch (15 March – May 1937), Major Werner Nielsen (May – 31 July 1937), Oberstleutnant Eduard Ritter von Schleich (1 August 1937 – 30 September 1938), Hauptmann Werner Palm (1 October 1938 – 27 June 1939) and Hauptmann Herwig Knüppel, who took command on 28 June 1939.

The Geschwaderstab (headquarters unit) was formed on 1 November 1938 in Düsseldorf and placed under the command of Oberst Eduard Ritter von Schleich. On this day, the Geschwader was renamed to Jagdgeschwader 132 (JG 132–132nd Fighter Wing) and was subordinated to Luftgaukommando IV (Air District Command). Also, on this day, I. and II. Gruppe of JG 234 were placed under the command of JG 132 and were then referred to as I. and II. Gruppe of JG 132. The Geschwaderstab was equipped with the Bf 109 D-1. On 8 December 1938, JG 132 was given the unit name "Schlageter", named after Albert Leo Schlageter. Schlageter was former member of the Freikorps who was executed by the French for sabotage and then became a martyr cultivated by the Nazi Party.

On 1 May 1939, the unit was named Jagdgeschwader 26 "Schlageter". One practical result of being a "named" unit was that for propaganda, if not necessarily operational, reasons, the wing was always among the first to receive new equipment; by January 1939 the Jagdgeschwader had received the newer Bf 109 E-1 which was highest performing fighter aircraft in the world at the time. I. Gruppe was commanded by Gotthard Handrick. Handrick served in Jagdgruppe 88 (J/88), Condor Legion, during the Spanish Civil War. Hauptmann Werner Palm commanded II. Gruppe, while III. Gruppe, formed 23 days into the war, was placed under Major Ernst Freiherr von Berg.