The Fokker D.XXIII was a Dutch single-seat fighter designed and built by Fokker. Only one aircraft was flown before the country was invaded by the Germans in May 1940.
The prototype first flew on 30 May 1939 powered by two Walter Sagitta I-SR liquid cooled vee piston engines. The trial flights identified problems with the cooling of the rear engine and general engine performance. It was proposed to use Rolls-Royce or Daimler-Benz engines in the production aircraft. Concerns were also raised about the pilot clearing the rear propeller if he had to bail out and an ejector seat was studied. The programme was abandoned in May 1940 when the German forces invaded the Netherlands.