HP

HP (also known as Health Points or Heart Points) is the amount of health the specified character has. If Luigi were to shine his flashlight on a ghost, the ghost's HP would show up below it. To lower the ghost's HP, Luigi must pull back the ghost into the vacuum, not allowing it to escape. When the ghost's HP reaches 0, it would then be sucked up by the vacuum. If a ghost attacks Luigi, he would lose a significant amount of Heart Points depending on the ghost that attacks him. If Luigi's HP were to reach 0, he would faint unconsciously and the player would lose all data back to when he or she last saved. Jars, ceiling fans and some other objects may give Luigi hearts in quantities of 10, 20, or 50. In Luigi's Mansion: Dark Moon, health is less common, yet it can still be found by searching around the rooms.

Normal Ghosts

 * Gold Ghost: 10 HP
 * Purple Puncher: 20 HP
 * Trash Can Ghost: 40 HP
 * Blue Twirler: 30 HP
 * Bowling Ghost: 0 HP
 * Ceiling Surprise: 0 HP
 * Waiter: 10 HP
 * Temper Terror: 10 HP
 * Flash: 20 HP
 * Blue Blaze: 30 HP
 * Purple Bomber: 0 HP

Bosses

 * Portrait Ghosts: 100 HP
 * Boos: Varies (30-300 HP)
 * King Boo: 500 HP

Normal Ghosts

 * Greenie: 10 HP
 * Hider: 15 HP
 * Gold Greenie: 20 HP
 * Sneaker: 25 HP
 * Slammer: 30 HP
 * Polterpup: 50 HP
 * Strong Greenie: 50 HP (100 HP)
 * Strong Hider: 75 HP
 * Gobber: 100 HP
 * Strong Sneaker: 100 HP
 * Strong Slammer: 150 HP (250 HP)
 * Strong Gobber: 200 HP (300 HP)
 * Creeper: Infinite HP

Mini-boss Ghosts

 * Poltergeist: 50 HP
 * Three Sisters
 * Sister Lucinda: 50 HP
 * Sister Belinda: 100 HP
 * Sister Herlinda: 150 HP
 * Ancient Poltergeist: 100 HP
 * Strong Poltergeist: 250 HP (200 HP)

Boss Ghosts

 * King Boo: 100 HP x 3 (300 HP in total)
 * The Brain: Varies 300 HP, 500 HP, 700 HP, 900 HP
 * Possessor Ghosts: Infinite HP

NOTES (Dark Moon specific):
 * Non-Boss Ghost HP increases by 5 HP every five floors in the ScareScraper.
 * Paranormal Shields grant Infinite HP to any ghost

Trivia
HP is also short for horsepower, the power of a car.