P56 may refer to:
, a submarine of the Royal Navy , a patrol vessel of Indian Navy Northrop XP-56 Black Bullet, an American prototype fighter aircraft Papyrus 56, a biblical manuscript Percival P.56 Provost, a British trainer aircraft P56, a state regional road in Latvia Prohibited Area 56, the prohibited airspace around the White House, U.S. Capitol and Naval Observatory in Washington D.C.