The Seer was a Mondasian Sea Devil.
He was the leader of a group of Sea Devils guarding Golgoth. A group of Cybermen attacked the Seer's island and killed everyone but him, since they only needed him to take them to Golgoth. However, Golgoth destroyed all the Cybermen. He kept the Seer with him for several days, and the Sea Devil finally died from lack of water. (COMIC: The Hungry Sea, The Dark Flame)