From the faerie lore of the Isle of Man, there comes the tale of the Lhiannon-Sidhe. Her name, in Gaelic, is generally rendered Leanan Sidhe, and it means the "fairy sweetheart" or the "fairy mistress."She is almost always depicted as female and beautiful beyond comparison. As with many of the fair-folk, she frequently wears green. This is the color of death where she comes from, and it is a warning sign to all those who might otherwise be entranced by her beauty. She is the original la belle dame sans merci of Keats, and her lovers all lead very brief lives.

In his Fairy and Folk Tales of Ireland, poet W.B. Yeats has this to say: "Most of the Gaelic poets, down to quite recent times, have had a Leanhaun Shee, for she gives inspiration to her slaves and is indeed the Gaelic muse... Her lovers, the Gaelic poets, died young. She grew restless and carried them away to other worlds, for death does not destroy her power." In the Isle of Man, this Dark Muse of Faerie is believed to have vampiric qualities, and she drains the life from the young men she takes to her bed, even as her kisses inspire them to greater heights in their arts.