In Greek mythology, Polyphemus (Πολύφημος) was the son of Elatus (or Poseidon) and Hippea. According to one source, he was married to Laonome, sister of Heracles. As a Lapith, he was remembered for having fought against the Centaurs in the days of his youth. Years later, he joined the expedition of the Argonauts. During their stay in Bithynia, Polyphemus was the one to hear Hylas cry as the youth was being dragged away by the nymphs, and when he helped Heracles search for Hylas, both were left behind by the Argo. Having settled in Mysia, Polyphemus founded the city Cius of which he became king. Later, however, he set out to search for his fellow Argonauts and died in the land of the Chalybes. He was buried at the seashore under a poplar tree.