Maddan was a legendary king of the Britons as accounted by Geoffrey ofMonmouth. He was the son of King Locrinus and Queen Gwendolen, who bothruled Britain separately.
He was born during the reign of Locrinus but soon after, his grandfatherCorineus of Cornwall died and his mother defeated Locrinus in battle. Hismother reigned for the fifteen years of Maddan's adolescence then sheabdicated in his favor. Soon after taking the throne, he married andbecame the father of Mempricius and Malin. For forty years he reignedpeacefully until his death when civil war broke out between his sons.