Produced in greater quantities than any other fighter (over 30,000), the Messerschmitt Me-109 was the principal German fighter of the Second World War, and served with other air forces until 1965. It was introduced in 1937.
Many variants were built, the first major round of modification coming when the Germans realized it was undergunned in comparison to potential enemy aircraft such as the Hawker Hurricane and Supermarine Spitfire. Its wing structure did not lend itself to more internal machine guns, so the successful Me-109F used two machine guns mounted over the engine, with a 20mm autocannon firing through the center of the propeller hub.
Given the strain on its aircraft industry, Germany tried to produce far too many modifications of the basic Me-109, making it a spare parts nightmare. Nevertheless, it served well in the Battle of Britain. Variants were produced in Czechoslovakia and Spain, and, somewhat ironically, became the backbone of the early Israeli Air Force.