Ghoul

Ghouls are slimy, buck-toothed, ugly creatures which live in the attics or barns of wizards. They are dim-witted and are content to throw things around now and then. Ghouls are relatively harmless creatures who live on spiders and moths (FB).

• A ghoul lives in the attic of the Burrow, just above Ron's room. The ghoul makes noises a lot (CS4, GF10) . When Ron was about to leave home to look for Horcruxes, Fred, George and Arthur Weasley transformed the ghoul to look like Ron with Spattergroit (DH6).
• Ghouls have been known to take up residence in neglected corners of other human structures, as well. There was a ghoul in the upstairs toilet at 12 Grimmauld Place (OP6), and and a ghoul stowed away on a transatlantic ship was partially responsible for the existence of Hidebehinds when it mated with a traveller's Demiguise (FB).
• The Ghoul Task Force in the Department for the Regulation and Control of Magical Creatures removes ghouls from Muggle homes (FB).