Deildegast

The deildegast is not an origin-mythic being but a postmortem condition described in Norwegian tradition: a person who in life enlarged holdings by moving a boundary stone becomes, after death, a deildegast. The earliest literary attestation cited in the supplied materials appears in the medieval poem Draumkvedet; the belief likely predates that mention but there is no definitive proof of earlier documentation.

In human guise a deildegast appears like an ordinary person but is noted for wearing outdated clothing (reflecting the fact many had died long before being seen). It was also said to be able to take the form of a bird, most commonly an owl; local observers called the bird form a "gasten."

The deildegast's defining compulsion is to haunt the vicinity of the boundary stone it or its offender moved and repeatedly attempt to lift and return the stone to its correct place. These attempts are futile — the stone will always slip — producing a sorrowful, recurring effort. Shape-change into a bird (often an owl) is attested. The tradition frames this condition as punitive and as a communal deterrent rather than as a wide-ranging threatening power.