D81 may refer to:
GER Class D81, class of twenty-five 0-6-0 steam locomotives for the Great Eastern Railway , Q-class destroyer of the Royal Australian Navy (RAN) , Admiralty type flotilla leader of the Royal Navy , Hawkins-class heavy cruisers built for the Royal Navy
See also .d81 or Commodore 1581, 3½-inch double-sided double-density floppy disk drive D. 81, Song "Auf den Sieg der Deutschen" for voice, two violins and cello (1813) by Franz Schubert