In Scandinavian folklore the nisse or tomte is considered to be a sprite who looks after the home. Folklorists generally would regard him as the spirit of the ancestor of the family who built the home. He is regarded as having a beard and wearing old fashioned rustic garb. Sometimes the tomte is regarded as having a single eye, like the cyclops. It appears to be attached, not so much to the house in which it dwells, as to the family which lives there.
Brad Steiger (born 1936), the well-known writer on the paranormal, claimed in an article in Fate magazine that his house in America, when he was young, was tenanted by a nisse. He ascribed poltergeist activity to it. This frightened him so much that on one occasion he crouched on the stairs, clutching a small bore rifle. This he did not feel the need to discharge, however, for he heard a sound of air and a tinkling laugh which indicated that the nisse had stopped its mischief. Later, the nisse adopted the habit of hiding papers of both Steiger and his wife.
It hardly looks as though this was an ancestor spirit. Perhaps the idea that the nisse was an ancestor is a later accretion to the legend.