HP3 or variant, may refer to:

HP3, a postcode for Hemel Hempstead, see HP postcode area hP3, a Pearson symbol Harry Potter and the Prisoner of Azkaban, the third Harry Potter novel Harry Potter and the Prisoner of Azkaban (film), the third Harry Potter film Handley Page Type C H.P.3, an airplane HP-3, a glider designed by Richard Schreder HP3, a type of photographic stock, see Ilford HP HP3, Heat Flow and Physical Properties Package, an instrument aboard the InSight Mars lander Hydrogen triphosphide

See also HP (disambiguation)