In Greek mythology, Augeas (or Augeias, /ɔːˈdʒiːəs/, Ancient Greek: Αὐγείας), whose name means "bright", was king of Elis and father of Epicaste. Some ancient authors say that Augeas was one of the Argonauts.^[1] He is known for his stables, which housed the single greatest number of cattle in the country and had never been cleaned, until the time of the great hero Heracles. The derivative adjective augean came to signify a challenging task, typically improving or fixing something that is currently in a bad condition.^[2][3]

Augeas's lineage varies in the sources: he was said to be either the son of Helios^[4] either by Nausidame^[5] or Iphiboe,^[6] or of Eleios,^[7] or of Poseidon, or of Phorbas and Hyrmine.^[8] In the latter account, Augeas was probably the brother of Actor,^[9] Tiphys^[10] and Diogeneia.^[11] His children were Epicaste, Phyleus, Agamede,^[12] Agasthenes,^[13] and Eurytus.^[14]

The fifth Labour of Heracles (Hercules in Latin) was to clean the Augean (/ɔːˈdʒiːən/) stables. Eurystheus intended this assignment both as humiliating (rather than impressive, like the previous labours) and as impossible, since the livestock were divinely healthy (immortal) and therefore produced an enormous quantity of dung (ἡ ὄνθος). Those stables had not been cleaned in over thirty years,^[15] and 3,000 cattle lived there. However, Heracles succeeded by rerouting the rivers Alpheus and Peneus to wash out the filth.

Augeas reacted angrily because he had promised Heracles one tenth of his cattle if the job was finished in one day. He refused to honour the agreement, and Heracles killed him after completing the tasks. Heracles gave his kingdom to Phyleus, Augeas' son, who had been exiled for supporting Heracles against his father.

According to the odes of the poet Pindar, Heracles then founded the Olympic Games:

the games which by the ancient tomb of Pelops the mighty Heracles founded, after that he slew Kleatos, Poseidon's godly son, and slew also Eurytos, that he might wrest from tyrannous Augeas against his will reward for service done.^[16]

Eurystheus discounted the success of this labour because the rushing waters had done the work of cleaning the stables and because Heracles was paid. Stating that Heracles still had seven labours to do, Eurystheus then sent Heracles to defeat the Stymphalian Birds.

• Apollodorus, The Library with an English Translation by Sir James George Frazer, F.B.A., F.R.S. in 2 Volumes, Cambridge, MA, Harvard University Press; London, William Heinemann Ltd. 1921. ISBN 0-674-99135-4. Online version at the Perseus Digital Library. Greek text available from the same website.
• Diodorus Siculus, The Library of History translated by Charles Henry Oldfather. Twelve volumes. Loeb Classical Library. Cambridge, Massachusetts: Harvard University Press; London: William Heinemann, Ltd. 1989. Vol. 3. Books 4.59–8. Online version at Bill Thayer's Web Site
• Diodorus Siculus, Bibliotheca Historica. Vol 1-2. Immanel Bekker. Ludwig Dindorf. Friedrich Vogel. in aedibus B. G. Teubneri. Leipzig. 1888-1890. Greek text available at the Perseus Digital Library.
• Gaius Julius Hyginus, Fabulae from The Myths of Hyginus translated and edited by Mary Grant. University of Kansas Publications in Humanistic Studies. Online version at the Topos Text Project.
• Pausanias, Description of Greece with an English Translation by W.H.S. Jones, Litt.D., and H.A. Ormerod, M.A., in 4 Volumes. Cambridge, MA, Harvard University Press; London, William Heinemann Ltd. 1918. Online version at the Perseus Digital Library
• Pausanias, Graeciae Descriptio. 3 vols. Leipzig, Teubner. 1903. Greek text available at the Perseus Digital Library.
• Scholia to Lycophron's Alexandra, marginal notes by Isaak and Ioannis Tzetzes and others from the Greek edition of Eduard Scheer (Weidmann 1881). Online version at the Topos Text Project.. Greek text available on Archive.org