The Jumo 205 aircraft engine was the most famous of a series of aircraft diesel engines produced by Junkers. The Jumo 204 first entered service in 1932. Later engines of this type comprised the experimental Jumo 206 and Jumo 208, with the Jumo 207 produced in some quantity for the Junkers Ju 86P and -R high-altitude reconnaissance aircraft, and the 46-meter wingspan, six-engined Blohm & Voss BV 222 Wiking flying boat. All three of these variants differed in stroke and bore and supercharging arrangements. In all, more than 900 of these engines were produced, in the 1930s and through most of World War II.

The aircraft diesel engine or aero diesel is a diesel-powered aircraft engine. They were used in airships and tried in aircraft in the late 1920s and 1930s, but were never widely adopted until recently. Their main advantages are their excellent specific fuel consumption, the reduced flammability and somewhat higher density of their fuel, but these have been outweighed by a combination of inherent disadvantages compared to gasoline-fueled or turboprop engines. The ever-rising cost of avgas and doubts about its future availability have spurred a resurgence in aircraft diesel engine production in the early 2010s.