Jackson: Sea of Monsters, Polyphemus is portrayed by Robert Maillet and voiced by Ron Perlman. Cynocephali - A race of dog-headed men from India. In The Blood of Olympus, Octavius obtained some Cynocephali from Triumvirate Holdings. In The Dark Prophecy, the Cynocephali are seen at the naming rehearsal held by Commodus as he prepares to invade the Waystation. In The Tyrant's Tomb, the Cynocephali are amongst the monsters used in Caligula's attack on Camp Jupiter. Echidna – Part woman, part snake. She is the wife of Typhon and the mother of Cerberus, Chimera, Hydra, the Nemean Lion, and Ladon as well as several others not in the series. She is first seen in The Lightning Thief as an old lady who owned a chihuahua which was actually Chimera in disguise. Echidna also detests that there is a marsupial that was named after her. She assisted Chimera in fighting Percy at the top of the St. Louis Arch. She and the Chimera disappeared after Percy dove into the water. Suzanne Cryer will portray Echidna in the TV show. Empousai – Seductive shapeshifting women who are similar in appearance to vampires, but have one shaggy donkey leg and one bronze leg. Two Empusa pose as cheerleaders in The Battle of the Labyrinth. In The Last Olympian, an unnamed Empousai appears as part of the truce party along with Prometheus, Morrain, and Ethan Nakaumura. She stated that she was among the things that was released from Pandora's pithos. Kelli – An Empousai that poses as a cheerleader in The Battle of the Labyrinth. She was killed by Annabeth. In The House of Hades, Kelli is among the Empousai that make their way to the Doors of Death so that Kelli can get even with Percy. However, Bob the Titan suddenly drops on Kelli and crushes her flat. Seraphone – An Empousai who distrusts Kelli and fears Hecate. In The House of Hades, Seraphone is among the Empousai that make their way to the Doors of Death. When they attack Percy and Annabeth, Annabeth tricks the Empousai into believing that Kelli was useless and weak and that she was leading them all into danger. Annabeth tells them to follow Serephone as she was older and wiser. Hearing this made Serephone happy and declared that she was the leader. Kelli became angry and killed Serephone. Tammi – An Empousai that poses as a cheerleader in