Poltergeist

"These big-headed know-it-alls have swollen brains (and egos) that afford them telekinetic power. Sadly, their sense of humor seems to be underdeveloped."— E. Gadd , Luigi's Mansion 2

Info
Their first apearence was in Luigi's Mansion 2, inside of the Gloomy Manor in mission A-3 "Quiet Please!" They have 50HP, and their main attack is throwing books or other items at Luigi.

It also Has two subspecies.The first subspecies encountered is the  Ancient Poltergeist. It has a coblalt blue body with a cyan brain. It first appears in C-2: Underground Expedition, where it steals one of the clock hands, and you then battle it in C-3: Roundhouse Brawl, it has 100 HP. The other is the  Final Boss ghost in the  ScareScraper   called   The Brain   and it is also the most powerful of all the Poltergeists.

Trivia

 * In the Beta of Luigi's Mansion 2, the stairs trap in the Gloomy Manor's Foyer, after Luigi sled down the stairs that became a slide, the ghost that appeared was not a Hider, it was a Poltergeist that did not have a swollen brain in his head as seen in the E3 2011 Trailer, but then it was changed to a Hider later in development of the game.
 * The Poltergeist is a Reference to the famous horror movie, Poltergeist.