This article is about the Aegyptus from Egyptian mythology. For the Book of Abraham reference, see Egyptus.

In Greek mythology, Aegyptus, or properly Aígyptos in Greek ("supine goat"), was the king of Egypt (which took its name from his, accoring to folk etymology; see the article Copt), the son of Belus and father of fifty sons who were all but one murdered by the fifty daughters of Aegyptus' twin brother, Danaus.

Aegyptus commanded that his sons marry the Danaides and Danaus fled to Argos, ruled by King Pelasgus. When Aegyptus and his 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, 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 later slew Danaus as revenge for the death of his brothers. Lynceus and Hypermnestra founded the lineage of Argive kings (the Danaan Dynasty). In some versions of the legend, the Danaides were punished in the underworld by being forced to carry water through a jug with holes, or a sieve, so that the water always leaked out.

Aegyptus is also the Latin spelling of Egypt, and the correct denomination for the Roman province.