D21 may refer to: Vehicles Aircraft Dewoitine D.21, a French fighter Fokker D.XXI, a Dutch fighter Lockheed D-21, an American reconnaissance drone Salmson D21 Phrygane, a French utility aircraft Ships , a Nueva Esparta-class destroyer of the Venezuelan Navy , a County-class destroyer of the Royal Navy , a Q-class destroyer of the Royal Navy , a Ruler-class escort aircraft carrier of the Royal Navy , a W-class destroyer of the Royal Navy , a Fletcher-class destroyer of the Spanish Navy Surface vehicles Allis-Chalmers D21, an American tractor D21 Navara, a Nissan Datsun pickup truck LNER Class D21, a class of British steam locomotives Other uses Arriflex D-21, a digital motion picture camera Chondroma D21 road (Croatia) D21 – Janeček method, an electoral system D21, a computer from Datasaab D-21 Special, a guitar made by Martin Guitar