#as well as their ancestor's contributions to Gaelic mythology and modern stories

[legend-collection]

Aos Sí

Aos sí  is the Irish name for a supernatural race in Celtic mythology – spelled sìth by the Scots, but pronounced the same – comparable to fairies or elves. They are said to descend from either fallen angels or the Tuatha Dé Danann, meaning the "People of Danu", depending on the Abrahamic or pagan tradition.

The aos sí are said to live underground in fairy forts, across the western sea, or in an invisible world that co-exists with the world of humans. This world is described in the Lebor Gabála Érenn as a parallel universe in which the aos sí walk among the living.

In modern Irish the people of the mounds are also called daoine sídhe  in Scottish mythology they are daoine sìth. They are variously said to be the ancestors, the spirits of nature, or goddesses and gods.

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In many Gaelic tales, the aos sí are later, literary versions of the Tuatha Dé Danann ("People of the Goddess Danu")—the deities and deified ancestors of Irish mythology. Some sources describe them as the survivors of the Tuatha Dé Danann who retreated into the Otherworld when fleeing the mortal Sons of Míl Espáine who, like many other early invaders of Ireland, came from Iberia. As part of the terms of their surrender to the Milesians, the Tuatha Dé Danann agreed to retreat and dwell underground. (In later interpretations, each tribe of the Tuatha Dé Danann was given its own mound.) Geoffrey Keating, an Irish historian of the early 17th century, equates Iberia with the Land of the Dead, providing a possible connection to the aos sí.

In folk belief and practice, the aos sí are often appeased with offerings, and care is taken to avoid angering or insulting them. Often they are not named directly, but rather spoken of as "The Good Neighbours", "The Fair Folk", or simply "The Folk". The most common names for them, aos sí, aes sídhe, daoine sídhe (singular duine sídhe) and daoine sìth mean, literally, "people of the mounds" (referring to the sídhe). The aos sí are generally described as stunningly beautiful, though they can also be terrible and hideous.

Aos sí are seen as fierce guardians of their abodes —whether a fairy hill, a fairy ring, a special tree (often a hawthorn) or a particular loch or wood. It is believed that infringing on these spaces will cause the aos sí to retaliate in an effort to remove the people or objects that invaded their homes. Many of these tales contribute to the changeling myth in west European folklore, with the aos sí kidnapping trespassers or replacing their children with changelings as a punishment for transgressing. The aos sí are often connected to certain times of year and hours; as the Gaelic Otherworld is believed to come closer to the mortal world at the times of dusk and dawn, the aos sí correspondingly become easier to encounter. Some festivals such as Samhain, Bealtaine and Midsummer are also associated with the aos sí.

Daoine maithe is Irish for "the good people", which is a popular term used to refer to the fairies in Irish folklore. Due to the oral nature of Irish folklore the exact origins of the fairies is not well defined. There are stories enough to support two possible origins. The fairies could either be fallen angels or the descendants of the Tuatha Dé Danann; in the latter case this is equivalent with Aos Sí. In the former case, it is said that the fairies are angels who have fallen from heaven, but whose sins were not great enough to warrant hell.

They are generally human-like, though there are exceptions such as the Puca or Mermaid. The defining features of the Irish fairies are their supernatural abilities and their temperament. If treated with respect and kindness, Irish fairies can be quite benevolent; however, if they are mistreated they will react cruelly.