A man from the village of Avardin, in Dunland. He is the younger brother of Madugan, one of many who stood with the Wayfarers at Amon Min when their commander, Oendir, was kidnapped by the witch Kalidah. After Madugan's death, Gwin became Brehir of Avardin in his brother's place.
Gwin helped the Wayfarers in their trek south through Dunland when they sought to return the ashes of a fallen ally to her homeland in Rohan. In return, they helped Gwin rescue his nephew from the pits of Isengard, where they also found Oendir's long-lost brother, Landuin.