Lludd and Llefelys (Welsh: Cyfranc Lludd a Llefelys, "The adventure or encounter of Lludd and Llefelys"[1]) is a Middle Welsh prose tale written down in the 12th or 13th century; it was included in the Mabinogion by Lady Charlotte Guest in the 19th century. It tells of the Welsh hero Lludd Llaw Eraint, best known as King Lud son of Heli in Geoffrey of Monmouth's Historia Regum Britanniae, and his brother Llefelys.