The Morane-Saulnier M.S.406 is a French fighter aircraft developed and manufactured by Morane-Saulnier starting in 1938. It was France's most numerous fighter during the Second World War and one of only two French designs to exceed 1,000 in number. At the beginning of the war, it was one of only two French-built aircraft capable of 400 km/h (250 mph) – the other being the Potez 630.

Aéroplanes Morane-Saulnier was a French aircraft manufacturing company formed in October 1911 by Raymond Saulnier and the Morane brothers, Léon and Robert. The company was taken over and diversified in the 1960s.