Edern ap Nudd (Latin: Hiderus;[1] Old French: Yder[2] or Ydier) was a knight of the Round Table in Arthur's court in early Arthurian tradition. As the son of Nudd (the Nu, Nut or Nuc of Old French, Arthurian romance), he is the brother of Gwyn, Creiddylad, and Owain ap Nudd. In French romances, he is sometimes made the king of a separate realm. As St Edern, he has two churches dedicated to him in Wales.