The origin of Cordelia in King Lear. Sometimes listed as Lludd's daughter, sometimes as Llyr's. In the Mabinogion, she is battled over by two jealous lovers--Gwythern and Gwyn ap Nudd. They war every Beltane, as prescribed by King Arthur, until the end of the world.
The confusion between Lludd and Llyr only adds to my belief that Lludd is a confluence of Nudd and Llyr into one god.