The Morane-Saulnier L, also known as the Morane-Saulnier Type L was a French parasol wing one or two-seat aeroplane of the First World War. The Type L became one of the first successful fighter aircraft when it was fitted with a single machine gun that fired through the arc of the propeller, which was protected by armoured deflector wedges. Its immediate effectiveness in this role launched an arms race in fighter development, and the Type L was swiftly rendered obsolete. The original Type L used wing warping for lateral control, but a later version designated Type LA was fitted with ailerons.
Built by Morane-Saulnier, large numbers of the Type L were ordered by the French Aviation Militaire at the outbreak of the war, being designated the MS.3. In total about 600 Type Ls were built and, in addition to the French air force, they served with the Royal Flying Corps, Royal Naval Air Service and the Imperial Russian Air Service.
The type was also produced under licence in Germany by Pfalz Flugzeugwerke as the unarmed A.I and A.II scouts, and later the E.III armed scout. A few Type Ls captured by Germany were fitted with a single German Spandau IMG 08 machine gun. These captured and converted aircraft are often mistaken for Pfalz E.IIIs.
About 450 aircraft were licence-built in Russia by Duks and Lebed works.
The Morane-Saulnier L was also built under licence in Sweden as the "Thulin D".