Gruagach

Gruagach means "long-haired one," and this Scottish fairy haunts castles and grand mansions, though unlike the house-dwelling brownie, it is the building it is attached to, not the family. If the house is demolished, the gruagach will disappear, never t be seen again. The spirit can be of either sex. A female gruagach once appeared on the island of Uist with long, golden hair, wore a pointed hat, and used a reed as a switch to keep her invincible cattle in order.
The gruagach manifests or cries out whenever joy or sorrow is coming to the family. At night, it tidies the castle, sweeps the floor, and rearranges the furniture. When it is heard doing so, the human inhabitants can be sure that visitors are about to arrive, and the fairy wants the pace to look its best.
The gruagach is a temperamental creature; sometimes it will finish the washing, or, at other times, despite the noise of work, things may be found in disorder or a resident tradesman's tools will be ruined. If the band is not taken off the spinning wheel at night, the gruagach will muddle all the work.
When servants annoy it, the "long-haired one" will punish them by knocking over water pitchers, unmaking the beds, putting dust in the meat, or slapping people on the side of the head. As long as the fairy is honored, no bad luck will befall the family's cows. Milkmaids were always careful to appease the fairy by pouring milk on certain stones for its consumption; otherwise, the gruagach would allow the cow to trample the corn or, if further offerings were neglected, cause the death of the cow.
In Ireland, the term is more loosely applied to a variety of fairy beings, such as ogres, goblins, giants, and even human magicians, druids, and heroes.