Sidhe

The sidhe is a term in Irish and Scottish Gaelic folklore used to describe a race of supernatural beings associated with the Otherworld. In traditional belief, the sidhe are the people of the sídhe, or fairy mounds, and in Irish myth they are often equated with the Aos Sí, the inhabitants of the Otherworld. The Tuatha Dé Danann, a prime group of gods in Irish myth, are said to have retreated into the sídhe after their battles with later conquerors and became the Aos Sí.

The sidhe are not a single uniform group. They are depicted as noble, often beautiful beings with magical powers, long lifespans, and abilities such as shapeshifting, weather control, and influence over animals and fate. They are commonly believed to reside in fairy mounds or hills, where fairy courts preside. The Daoine Sí is a broader term for the people of the sídhe, including beings such as the bean sí (fairy woman) and the Leanan sídhe (fairy lover), among others. Some sidhe are benevolent or helpful to humans, while others are mischievous or dangerous; many tales warn of crossing them, breaking their laws, or neglecting proper respect. Interactions with humans often involve offerings, oaths, or enchanted deceit, and fairy forts or ring-forts are viewed as liminal and potentially perilous places.

In modern usage, sidhe is frequently employed in literature and popular culture to denote Celtic-inspired elves or noble fairies, appearing in fantasy settings to evoke Celtic myth.