The Messerschmitt Bf 110, often known unofficially as the Me 110, is a twin-engined Zerstörer, fighter-bomber, and night fighter (Nachtjäger) developed in Nazi Germany in the 1930s and used by the Luftwaffe during World War II. Hermann Göring was a proponent of the Bf 110, believing its heavy armament, speed, and range would make the Bf 110 the Luftwaffe’s premier offensive fighter. Early variants were armed with two MG FF 20 mm cannon, four 7.92 mm MG 17 machine guns, and one 7.92 mm MG 15 machine gun for defence. Development work on an improved type to replace the Bf 110 - the Messerschmitt Me 210 - began before the war started, but its shakedown troubles resulted in the Bf 110 soldiering on until the end of the war in various roles. Its intended replacements, the aforementioned Me 210 and the significantly improved Me 410 Hornisse, never fully replaced the Bf 110.

A heavy fighter is a historic category of fighter aircraft produced in the 1930s and 1940s, designed to carry heavier weapons or operate at longer ranges than light fighter aircraft. To achieve performance, most heavy fighters were twin-engine, and many had multi-place crews; this was in contrast to light fighters, which were typically single-engine and single-crew aircraft. In Germany, these larger fighters were known as Zerstörer ("destroyer").