Rat

Rats of Kitchen Land appeared in Super Mario Land 3: Wario Land. They are larger and more humanoid than many rodents of the Mario series, and are also extraordinarily ill-tempered. They are proficient in the use of knives and will not hesitate to toss one Wario's way if they see him.

In Paper Mario: The Thousand-Year Door, Jolene told Grubba that the disturbance in the Glitz Pit storeroom must have been due to a "rat or something." This explanation calmed Grubba, implying that a rat, or at least certain rats, are common pests in the Mushroom World.