In Irish and Scottish folklore, the Sluagh were the spirits of the restless dead. Sometimes they were seen as sinners, or generally evil people who were welcome in neither heaven nor hell, nor in the Otherworld, who had also been rejected by the Celtic deities and by the earth itself. Whichever the underlying belief, they are almost always depicted as troublesome and destructive. They were seen to fly in groups like flocks of birds, coming from the west, and were known to try to enter the house of a dying person in an effort to carry the soul away with them. West-facing windows were sometimes kept closed to keep them out. Some consider the Sluagh to also carry with them the souls of innocent people who were kidnapped by these destructive spirits. Lewis Spence writes in 'The Magic Arts in Celtic Britain': "In the Western Isles of Scotland the Sluagh, or fairy host, was regarded as composed of the souls of the dead flying through the air, and the feast of the dead at Hallowe'en was likewise the festival of the fairies."
In the Legacy of Kainvideo game series, Sluagh are among the enemies that Raziel encounters in the Spectral Realm. They are scavenging, animalistic creatures that prey on souls and usually prefer to flee from Raziel unless cornered or in a group. Raziel can easily weaken them into a transparent state in which he can devour them to replenish his own health. In the Merry Gentry series by Laurell K. Hamilton, the Slaugh are seen as a group of fae lesser than the Seelie and Unseelie. These fae are the more monstrous and strange fae. The kind of creatures which make up nightmares and ride in the Wild Hunt which can make one crazy if looked upon. One of Merry's lovers, Sholto, is the king of the Slaugh and Merry becomes queen later in the series. In the DeathSpeaker Codex series by Sonya Bateman, the Slaugh are a group of fae separate from the Seelie and Unseelie. Three of the sub-characters, Nyantha, Nix and Shade are Slaugh and help the main character throughout the storyline.
