Sluagh

The Sluagh ('host' or 'crowd') were the spirits of dead sinners refused entry to heaven and refused entry to hell — the truly lost dead. They travel as a swarm, dark birds against the western sky, and are most dangerous at Samhain. They came in from the west because that was the direction of the dead. They tried to enter the homes of dying people to carry off the soul before it could be received elsewhere.

Seen as a flock of dark birds or shadowy figures moving against the sky from the west. Up close, they appear as human figures, pale and haggard, with hollow eyes. They moved in groups and their passage created cold winds.

Could carry off the souls of the dying if windows were left open. Could wound the living with fairy darts (flint arrowheads). Could force a living person to accompany them for a night, compelling them to attack other living people before returning them, exhausted and broken.