The Minotaur was born from a curse and a broken promise. King Minos of Crete, the most powerful ruler in the Aegean Sea, had prayed to Poseidon, the god of the sea whose trident could split the earth and raise islands from the waves, to send him a sign of divine favor. Poseidon answered by sending a magnificent white bull from the depths of the ocean, a beast of perfect beauty and strength, and commanded Minos to sacrifice it in his honor. But Minos, greedy and proud, looked upon the bull and could not bear to destroy it. He kept it for himself and sacrificed a lesser animal instead. Poseidon, enraged by the insult, turned the bull wild and then struck Minos's wife Pasiphae with a madness so terrible that she fell in love with the beast. She confessed her shameful desire to Daedalus, the master craftsman and inventor who had built the Labyrinth for Minos and who was famous for creating wings of wax and feathers that allowed him and his son Icarus to fly. Daedalus, bound by the king's command, built a hollow wooden cow covered in real hide, and Pasiphae climbed inside it. From that unnatural union came the Minotaur, a creature with the head of a bull and the body of a man, who bellowed with a voice that shook the palace walls and whose hunger was for human flesh rather than grass or grain.

Minos, horrified by what his wife had done, consulted the oracle at Delphi, the sacred shrine of Apollo where the priestess Pythia spoke the words of the god, and was told that the monster must be hidden rather than killed. Daedalus was commanded to build a prison so complex that no one who entered could ever find the way out, and he constructed the Labyrinth, a maze of twisting corridors, dead ends, and false turns that spread beneath the palace of Knossos like the roots of an enormous tree. The Minotaur was placed at its center, and Athenian youths and maidens were sent as tribute to feed him. This tribute was the price Athens paid for the death of Minos's son Androgeos, who had been killed by the Athenians during the Panathenaic Games, either through jealousy or by accident, depending on which story is told. Every nine years, or some say every year, a ship with black sails sailed from Athens to Crete carrying fourteen young people, and none of them ever returned. The Minotaur grew larger and more terrible with each feeding, and the Labyrinth became a place of dread throughout the Greek world.

The defining episode of the Minotaur's story came when the hero Theseus, the son of King Aegeus of Athens, volunteered to go to Crete as one of the tribute youths. Theseus was already famous for his strength and courage, having killed the bandit Periphetes, who beat travelers with a bronze club; the giant Sinis, who tied men to bent pine trees and tore them apart; and the Crommyonian Sow, a monstrous pig that ravaged the countryside near Corinth. He had also slain the Minotaur's half-brother, the white bull of Marathon, a wild beast that had been sent by Poseidon to terrorize the plain of Marathon. When Theseus arrived in Crete, Ariadne, the daughter of Minos and Pasiphae, fell in love with him. She went to Daedalus and learned the secret of the Labyrinth: there was only one path to the center, and the trick was to keep one's hand on one wall and never let go. Ariadne gave Theseus a ball of thread, and told him to tie one end to the entrance and unwind it as he walked, so that he could follow it back out. She also gave him a sword, for the Minotaur could not be killed with bare hands.

Theseus entered the Labyrinth, unwinding the thread behind him, and walked through the darkness and the stench of old bones and rotting flesh until he reached the centre. The Minotaur was waiting, a hulking shape in the shadows, his bull's head lowered and his human hands reaching out to seize his prey. The two fought in the darkness, and Theseus, using his superior speed and the sword Ariadne had given him, struck the monster down. Some say he used his fists alone, beating the Minotaur until the beast collapsed. Others say he wrestled the creature and broke its neck. In either case, the Minotaur died in the place where he had been born, and Theseus followed the thread back to the entrance, where Ariadne was waiting. Together they fled Crete, though Theseus later abandoned Ariadne on the island of Naxos, where the god Dionysus found her and made her his bride. Theseus sailed back to Athens, and in his joy he forgot to change the black sails of mourning for white sails of victory, a mistake that caused his father Aegeus to believe his son was dead and throw himself from the cliff into the sea that now bears his name, the Aegean.

The Minotaur's death did not end the story of the Labyrinth, which remained beneath the palace of Knossos as a monument to Minos's power and Daedalus's genius. Daedalus himself was imprisoned in the Labyrinth by Minos for helping Ariadne betray the king, and he escaped only by building wings of wax and feathers for himself and his son Icarus. Icarus flew too close to the sun, the wax melted, and he fell into the sea and drowned, giving his name to the Icarian Sea. The Minotaur's image appeared in Greek art for centuries, painted on vases, carved on gems, and described in poetry as the ultimate symbol of the monster hidden at the heart of power. In the modern world, the word "labyrinth" still describes any maze of bewildering complexity, and the Minotaur has become a symbol of the beast within, the part of human nature that is half-civilised and half-savage. His story has been retold in novels, films, and psychological studies, and the archaeological site of Knossos, with its maze-like palace ruins, continues to draw visitors who walk the corridors where the Minotaur once waited in the dark.