Orthus had reformed along with Geryon. Although his official master is Geryon, he tends to listen more to Eurytion as he takes care of him, unlike Geryon. Similar to the ancient myths (Hercules), Percy Jackson, came to the ranch and killed Geryon, but unlike Hercules, he spared Orthus as he did not participate in defending his master because Eurytion had told him to stay back during the fight between Percy and Geryon.
|Species:||Centaur | Cyclopes | Dragon | Drakon | Eidolons | Empousa | Fire-Breathing Horse | Giants | Gorgon | Harpy | Hyperborean Giant | Ichthyocentaur | Karpoi | Katobleps | Laistrygonian Giant | Lycanthrope | Merpeople | Nikai | Nymphs | Pegasus | Satyr | Skolopendra | Stymphalian Birds | Telekhine | Blemmyae|
|Friendly Monsters:||Argus | Blackjack | Briares | Chiron | Don | Ella | Festus | Gleeson Hedge | Gray |Grover Underwood | Hippocampus | Mellie | Mrs. O'Leary | Ophiotaurus | Peleus | Scipio | Tyson | Tempest|
|Enemy Monsters:||Agrius and Oreius | Arachne | Basilisk | Charybdis and Scylla | Chimera | Chrysaor | Clazmonian Sow | Colchis Bull | Echidna | Euryale | Geryon | Joe Bob | Kampê | | Nanette | Manticore | Medusa | Minotaur | Nemean Lion | Polyphemus | Sphinx | Stheno | Typhon | Scythian Dracanae|
|Neutral Monsters:||Carnivorous Sheep | Cerberus | Erymanthian Boar | Gray Sisters | Gorgons | Furies | Flesh-Eating Horse | Gryphon | Siren|