P9 or P-9 may refer to: Planet Nine, a hypothetical new planet in the far outer solar system Boeing XP-9, a prototype fighter aircraft from the 1930s Heckler & Koch P9, a semi-automatic pistol Springfield Armory P9, a semi-automatic pistol Peruvian Airlines IATA airline designator P9 (band), a Brazilian boyband Power Nine, a trading cards game of Magic: The Gathering Psyclon Nine, an aggrotech band P-9 Project See also 9P (disambiguation)