Who killed the Minotaur?

In Greek mythology, the Minotaur is a mythical creature portrayed in Classical times with the head of a bull and the body of a man or, as described by Roman poet Ovid, a being "part man and part bull". The Minotaur dwelt at the center of the Labyrinth, which was an elaborate maze-like construction designed by the architect Daedalus and his son Icarus, on the command of King Minos of Crete. The Minotaur was eventually killed by the Athenian hero Theseus.

Because of a past wrong, Athens was forced to ship off young people to Crete every few years. There, boys and girls were devoured by Minotaur. Theseus, Prince of Athens, decided to put a stop to this and sailed off to slay the beast. He promised his father, King Aegeus, that he'll change the black sail of the ship to white on his return journey to show that he survived.

Theseus managed to slay the Minotaur with the help of the beautiful Cretan princess, Ariadne, whom he ended up marooning on an island on the way back to Greece. As Theseus approached Athens, he was so full of himself that he forgot to change the sail of is ship to white. When Aegeus saw the black-sailed ship approaching, he assumed that Theseus is dead and hurled himself into what is now call the Aegean Sea. Theseus became the King of Athens, but lost his father.