In Greek mythology, Danaus (//; Ancient Greek: Δαναός Danaós) was the king of Libya. His myth is a foundation legend (or re-foundation legend) of Argos, one of the foremost Mycenaean cities of the Peloponnesus. In Homer's Iliad, "Danaans" ("tribe of Danaus") and "Argives" commonly designate the Greek forces opposed to the Trojans.
Danaus, was the son of King Belus of Egypt and the naiad Achiroe, daughter of the river god Nilus. He was the twin brother of Aegyptus, king of Arabia while Euripides adds two others, Cepheus, King of Ethiopia and Phineus, betrothed of Andromeda.
Danaus had fifty daughters, the Danaides, twelve of whom were born to the naiad Polyxo; six to Pieria; two to Elephantis; four to Queen Europa; ten to the hamadryad nymphs Atlanteia and Phoebe; seven to an Ethiopian woman; three to Memphis; two to Herse and lastly four to Crino. According to Hippostratus, Danaus had all these progeny begotten by Europa, the daughter of Nilus. In some accounts, Danaus married Melia while Aegyptus consorted with Isaie, these two women were daughters of their uncle Agenor, King of Tyre, and their possible sister, Damno who was described as the daughter of Belus.
After Aegyptus commanded that his fifty sons should marry the Danaides, Danaus elected to flee instead, and to that purpose, he built a ship by the advice of Athena, the first ship that ever was. In it, he fled to Argos, to which he was connected by his descent from Io, a priestess of Hera at Argos, who was wooed by Zeus and turned into a heifer and pursued by Hera until she found asylum in Egypt. Argos at the time was ruled by King Pelasgus, the eponym of all autochthonous [indigenous] inhabitants who had lived in Greece since the beginning, also called Gelanor ("he who laughs"). The Danaides asked Pelasgus for protection when they arrived, the event portrayed in The Suppliants by Aeschylus. Protection was granted after a vote by the Argives.
When Pausanias visited Argos in the 2nd century CE, he related the succession of Danaus to the throne, judged by the Argives, who "from the earliest times ... have loved freedom and self-government, and they limited to the utmost the authority of their kings":
The sanctuary of Apollo Lykeios ("wolf-Apollo", but also Apollo of the twilight) was still the most prominent feature of Argos in Pausanias' time: in the sanctuary the tourist might see the throne of Danaus himself, an eternal flame, called the fire of Phoroneus.
When Aegyptus and his fifty sons arrived to take the Danaides, Danaus gave them, to spare the Argives the pain of a battle. However, he instructed his daughters to kill their husbands on their wedding night. Forty-nine followed through, and subsequently buried the heads of their bridegrooms in Lerna; but one, Hypermnestra, refused because her husband, Lynceus, honored her wish to remain a virgin. Danaus was angry with his disobedient daughter and threw her to the Argive courts. Aphrodite intervened and saved her. Lynceus and Hypermnestra then began a dynasty of Argive kings (the Danaid Dynasty). Some sources relate that Amymone, the "blameless" Danaid, and/or Bryce (Bebryce) also spared their husbands.
In some versions, Lynceus later killed Danaus as revenge for the death of his brothers.
The remaining forty-nine Danaides had their grooms chosen by a common mythic competition: A foot-race was held and the order in which the potential Argive grooms finished decided their brides (compare the myth of Atalanta). Two of the grooms were Archander and Architeles, sons of Achaeus: They married Scaea and Automate respectively.
In later accounts, the Danaides were punished in Tartarus by being forced to carry water in a jug to fill a bath without bottom (or with a leak) and thereby wash off their sins, but the bath was never filled because the water was always leaking out.
Another account of the travels of Danaus gave him three daughters, Ialysos, Kamiros and Lindos, who were worshipped in the cities that took their names in the island of Rhodes, Ialysos, Kamiros and Lindos (but see also Cercaphus). According to Rhodian mythographers who informed Diodorus Siculus, Danaus would have stopped and founded a sanctuary to Athena Lindia on the way from Egypt to Greece. Herodotus heard that the temple at Lindos was founded by Danaus' daughters. Ken Dowden observes that once the idea is dismissed that myth is directly narrating the movements of historical persons, that the loci of Danaian institutions at Lindos in Rhodes as well as at Argos suggests a Mycenaean colony sent to Rhodes from the Argolid, a tradition, in fact, that Strabo reports.
Danaus was credited as the inventor of wells and said to have migrated from Egypt about 1485 B.C. into that part of Greece which had been previously known as Argos Dipsion. Notes in Pliny the Elder's, Natural History also added that:
The epic Danais was written by one of the cyclic poets; the name of the author and the narration of these events does not survive, but the Danaid tetralogy of Aeschylus undoubtedly draws upon its material. It is represented in the table of epics in the received canon on the very fragmentary "Borgia table" as "Danaides".
A U.S. federal judge used the version of the legend in which the Danaides are forced to perform an impossible task as a simile for the judge's task of determining whether a case "arises under" the Constitution, laws or treaties of the United States.