This list of mythical creatures that begin with this letter and I am constantly gathering information from each continent, and is continually being updated.
Leanan Sidhe (Celtic)
The Leannán Sidhe, which means the fairy lover, once one of the De Danann who were banished to the mounds by iron-armed Gaelic invaders, and her embrace is deadly. She is known through the lands of the Gael, Scotland and among the Manx, offering wisdom and beauty to the young men of Ireland who were talented poets, artists, musicians and writers.
While she herself has no face, or at least she has never been described, when these men set eyes upon her she becomes the most beautiful woman they have ever seen, and they devote themselves to her until their obsession ends in madness and a terrible death, either by their own hand or by wasting away!