Greek Name Transliteration Latin Spelling Translation
Κυων Ορθρος
Κυων Ορθος
Kyôn Orthros
Kyôn Orthos
Cyon Orthrus
Cyon Orthus
Dog Morning Twilight
(kyôn, orthros)
Orthrus slain | Athenian red-figure kylix C6th B.C. | Antikensammlungen, Munich

Two-headed Orthrus slain, Athenian red-figure
kylix C6th B.C., Antikensammlungen, Munich

KYON ORTHROS (or Orthus) was a two-headed, serpent-tailed dog, a brother of monsters such as Kerberos and the Khimaira. He mated with the latter, siring the Sphinx and Nemean Lion.

His master was the three-bodied giant Geryon, king of the sunset isle of Erytheia. Orthros was set to guard his master's fabulous herd of red-skinned cattle. When Herakles was sent to fetch these as one of his twelve labours, he slew Orthros, the herdsman Eurytion and Geryon.

The word orthros in Greek means "morning twilight." His name was also spelt Orthos, after another word meaning "straight" or "height."

TYPHOEUS & EKHIDNA (Hesiod Theogony 309, Apollodorus 2.106, Quintus Smyrnaeus 6.249 & 260)
SPHINX, NEMEIAN LION (by Khimaira) (Hesiod Theogony 326)


ORTHRUS (Orthros), the dog of Geryones, who was begotten by Typhon and Echidna. (Hes. Theog 293; Apollod. ii. 5. § 10.)

Source: Dictionary of Greek and Roman Biography and Mytholog.

Hesiod, Theogony 326 ff (trans. Evelyn-White) (Greek epic C8th or C7th B.C.) :
"But she [the Khimaira or perhaps Ekhidna] in love with Orthos, mothered the deadly Sphinx . . . and the Nemeian lion."

Hesiod, Theogony 309 :
"First she [Ekhidna] bore him [Typhon] Orthos, who was Geryones' herding dog."

Hesiod, Theogony 293 ff :
"[Herakles] killed Orthos and the oxherd Eurytion out in that gloomy meadow beyond the fabulous Okeanos."

Pindar, Isthmian Ode 1 ep 1 (trans. Conway) (Greek lyric C5th B.C.) :
"Alkmene bore that dauntless son [Herakles], to whom long since the fierce hounds of Geryon yielded in trembling terror."

Pseudo-Apollodorus, Bibliotheca 2. 106 - 108 (trans. Aldrich) (Greek mythographer C2nd A.D.) :
"He [Geryon] owned crimson-colored cattle, which were herded by Eurytion and protected by Orthos, the hound with two heads born of Ekhidna and Typhon . . . When he [Herakles] reached Erytheia he camped on Mount Abas. The dog smelled him there and went after him, but he struck at it with his club, and when the cowherd Eurytion came to help the dog, he slew him as well."

Quintus Smyrnaeus, Fall of Troy 6. 249 ff (trans. Way) (Greek epic C4th A.D.) :
"There [depicted on the shield of Eurypylos son of Herakles] lay the bulk of giant Geryon dead mid his kine . . . Before him slain lay that most murderous hound Orthros, in furious might like Kerberos his brother-hound: a herdman lay thereby, Eurytion, all bedabbled with his blood."

Orthrus | Greek vase painting
Orthrus | Greek vase painting
Heracles, Geryon & Orthrus | Greek vase painting


Orthros may have originally represented the constellations Canis Major and Minor, the two heavenly canines forming the double-head of Orthros. The chief star of Canis Major was Seirios, the dog star, whose dawn rising was thought to bring on the scorching heat of mid-summer. The name kyôn Orthros indeed means "the dog of morning twilight." Just as Orthros represented the heat of summer, his mate the Khimaira, may have presided over the frosty chill of winter, with her December rising in the form of Capricorn. However nothing survives of this in any extant collection of Greek star myths.


  • Hesiod, Theogony - Greek Epic C8th-7th B.C.
  • Pindar, Odes - Greek Lyric C5th B.C.
  • Apollodorus, The Library - Greek Mythography C2nd A.D.
  • Quintus Smyrnaeus, Fall of Troy - Greek Epic C4th A.D.