The Fokker E.III was the main variant of the Eindecker (literally meaning "one wing") fighter aircraft of World War I.

The E.III retained the same 75 kW (100 hp) Oberursel U.I engine, and therefore also used the larger-diameter "horseshoe" pattern cowling that also mandated the inclusion of the E.II's soffit-like extensions to the sides of the upper nose sheet metalwork, but had a larger 81 L (21.5 gal) drum-shaped main fuel tank just behind the cockpit, which increased the Eindecker's endurance to about 2+1⁄2 hours, an hour more than the E.II.

The E.III was the first type to arrive in sufficient numbers to form small specialist fighter units, Kampfeinsitzer Kommandos (KEK) in early 1916.

Previously, Eindeckers had been allocated singly, just as the E.I and E.II had been, to the front-line Feldflieger Abteilungen that carried out reconnaissance duties.

The only known surviving original Eindecker, bearing IdFlieg serial number 210/16, was brought down in the Somme area in 1916 by the British and then evaluated by the War Office until it was transferred to the London Science Museum in 1918.