Orthus

In Greek mythology, Orthrus (Greek: Ὄρθρος, Orthros) or Orthus (Greek: Ὄρθος, Orthos) was, according to the mythographer Apollodorus, a two-headed dog who guarded Geryon's cattle and was killed by Heracles. He was the offspring of the monsters Echidna and Typhon, and the brother of Cerberus, who was also a multi-headed guard dog.

According to Hesiod, Orthrus was the father of the Sphinx and the Nemean Lion, though who Hesiod meant as the mother, whether Echidna, the Chimera, or Ceto, is unclear.

Orthrus and his master Eurytion were charged with guarding the three-headed, or three-bodied giant Geryon's herd of red cattle in the "sunset" land of Erytheia ("red one"), an island in the far west of the Mediterranean.Heracles killed Orthrus, and later slew Eurytion and Geryon before taking the red cattle to complete his tenth labor. According to Apollodorus Heracles killed Orthrus with his club, although in art Orthrus is sometimes depicted pierced by arrows.

The poet Pindar refers to the "hounds of Geryon" trembling before Heracles. Pindar's use of the plural "hounds" in connection with Geryon is unique. He may have used the plural because Orthus had multiple heads, or perhaps because he knew a tradition in which Geryon had more than one dog.

Depictions of Orthrus in art are rare, and always in connection with the theft of Geryon's cattle by Heracles. He is usually shown dead or dying, sometimes pierced by one or more arrows.

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