P9

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