In Greek mythology, Orthrus (also called Orthros, Orthos, Orthus, Orth and Orphus) (gr. Ὄρθρος) was a two-headed dog. He was owned by the winged titan, Geryon. Orthrus and his master, Eurytion, were charged with guarding Geryon's herd of red cattle. Heracles eventually killed Orthrus, Eurytion, and Geryon, before taking the red cattle to complete his tenth labor.
Orthrus was the son of Echidna and Typhon. His siblings included Chimera, Cerberus, the Lernaean Hydra, Ethon, Ladon, and sometimes the Sphinx and Nemean Lion. Because of the varying geneologies, he may be the father of the Sphinx and the Nemean Lion with either Echidne or Chimera. Due to his mother's relation to Heracles (taken from Herodotus), his half-siblings include Agathyrsi, Gelonus, and Scytha.
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