The bean sídhe (woman of the sídhe) belongs to the world of Irish supernatural belief, appearing as a beautiful or terrifying woman whose keening foretells the death of a member of certain families. She links the world of the fairy mounds — the sídhe — to the human world through the medium of lamentation, making her simultaneously a mourner and a death omen. In poetry she merges with the caoineadh tradition, since her voice is itself a keen. Nora Hopper Chesson and other Revival poets found in the bean sídhe an image of overwhelming feminine grief and supernatural beauty perfectly suited to their aesthetic programme.

The bean sídhe is the specific female spirit of the fairy mound, often conflated with the banshee but originally distinct as a guardian or inhabitant of the otherworld. In early poetry, she might appear as a lover or guide, while in later folklore, her role narrows to the death-messenger. Poets use her to explore the allure and danger of the supernatural feminine, often depicting her as beautiful yet terrifying. Her presence signals a breach in the ordinary world, inviting characters into adventures that challenge their humanity.