He and his brother, Otus are the sons of Poseidon. They are strong and aggressive giants, growing by nine fingers every month, nine fathoms tall at age nine and only outshone in beauty by their step-brother, Orion. The brothers wanted to storm Mt. Olympus and gain Artemis for Otus and Hera for Ephialtes. Ares tried to stop them, but they imprisoned him in a large bronze jar. In the end, Ephialtes and Otus are slain by the arrows of Artemis and Apollo.