The Daoine Sidhe is mentioned but not seen in the game.
The aos sí is the Irish term for a supernatural race in Irish mythology and Scottish mythology (usually spelled Sìth, however pronounced the same), comparable to the fairies or elves. They are said to live underground in fairy mounds, across the western sea, or in an invisible world that coexists with the world of humans. In Irish literature 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.