D51

D51 or D-51 may refer to:
 * D-51, a Japanese popular music group
 * JNR Class D51, a Japanese steam locomotive
 * HMS Atheling (D51), a 1942 British Royal Navy escort aircraft carrier
 * HMS Chevron (R51), a 1945 British Royal Navy destroyer, later re-designated D51
 * D51 road (Croatia), a state road
 * the ICD-10 code for vitamin B12 deficiency anemia