Polterkitty

Polterkitty is an enemy ghost encountered in Luigi's Mansion 3. Polterkitty is Hellen Gravely's pet cat that helps her through the game by stealing the elevator buttons from Luigi. Polterkitty also serves as a recurring boss in the game.

Biography
While Polterkitty doesn't appear at first in the game like Steward, she is first seen after Luigi rescues one of the toads, resting on Hellen Gravely's lap while the latter watches Luigi's progress in the hotel.

Trivia

 * Polterkitty serves as an evil counterpart to Polterpup and both share a similar behavior.
 * Polterkitty is one of the few antagonists in Luigi's Mansion to be an animal-based ghost, the other being Captain Fishook who is a shark.