After ascending the throne of the island of Crete, Minos competed with his brothers as ruler. Minos prayed to the sea god Poseidon to send him a snow-white bull as a sign of the god's favour. Minos was to sacrifice the bull to honor Poseidon, but owing to the bull's beauty he decided instead to keep him. Minos believed that the god would accept a substitute sacrifice. To punish Minos, Poseidon made Minos' wife Pasiphaë fall in love with the bull. Pasiphaë had the craftsman Daedalus fashion a hollow wooden cow, which she climbed into in order to mate with the bull. The monstrous Minotaur was the result.

Pasiphaë nursed the Minotaur but he grew in size and became ferocious. As the unnatural offspring of a woman and a beast, the Minotaur had no natural source of nourishment and thus devoured humans for sustenance. Minos, following advice from the oracle at Delphi, had Daedalus construct a gigantic labyrinth to hold the Minotaur. Its location was near Minos' palace in Knossos.