King Gradlon is a legendary figure from Breton folklore, often associated with the city of Ys, a mythical place said to be submerged beneath the sea. He is depicted as a wise and powerful ruler who built the city to protect his people from invaders and the harsh elements. In the tales, Gradlon is known for his strong connection to the sea and his tragic fate, as he ultimately loses his kingdom to the ocean's depths. His story reflects themes of pride, loss, and the consequences of human actions, making him a significant character in Breton mythology.