The Polterkitty is a purple cat with blue eyes, a white necklace and three long tails. She has an alternate form which gives her a panther-like appearance when she attacks.
Polterkitty will steal the ninth elevator button after the Godzilla ghost goes down. She is first seen as Luigi tries to insert the button to make his way to the next floor, and then grabs the button and runs off as he tells her to stop. Luigi must find her in one of the rooms on floor eight and shock her with the Strobulb the Polterkity will then turn into a huge monster and try to attack Luigi, he must turn away from her and wait until she goes to attack to shock and suck her with the Poltergust. However, she will lose only one of her tails and change back to her normal from and run away in pain. When Luigi finds and shocks her again, she go through the floor into the seventh floor to make her getaway. Luigi must find her in one of the rooms, shock her again as she attacks and suck up her second tail. When Luigi finds her again in another room and sucks her third tail, she will drop the elevator button. Polterkitty is seen again after Luigi obtains the fourteenth button, but she will be sucked up instead of her tail upon defeat.
- The character is a dark parallel to the Polterpup. They both steal items, but she has more of a sadistic bent, whereas the Polterpup just wanted to have fun. Luigi is also scared of the Polterkitty.
- She, the Polterpup, the Clockwork Soldiers from the first game, and the Disco Goobs are the only ghosts in the Luigi's Mansion franchise to have legs.