The Minotaur was a being with the head of a bull and the body of a man. He was the subject of several myths recorded in Greek mythology. (PROSE: Mythical Monsters, A History of Humankind) There also existed an extraterrestrial species of Minotaurs, related to the Nimons, who fed on faith, (TV: The God Complex) and several other similar-looking species. (COMIC: Minor Trouble, Agent Provocateur)
The Third Doctor learned that the Minotaur was real during a trip to Atlantis. The creature was formerly a member of Dalios's court, a great athlete who desired the strength of a bull and a long life in which to use it. Kronos granted him his wish, and the creature was made guardian of the Crystal of Kronos until the Doctor defeated it. (TV: The Time Monster)
The Minotaur was imprisoned by King Minos of Crete in the middle of a huge especially-designed maze built at Knossos, which was called the Labyrinth. Forced to pay tribute to Minos, Athens sent seven young men and seven young women every nine years to be devoured by the Minotaur. (PROSE: A History of Humankind) According to another account, the Minotaur was imprisoned by the King of Minos, and the sacrifices were not foreigners.
One of the tasks set to the superhuman hero Hercules was to capture the Minotaur, known by then as the "great bull of the King of Minos". Hercules walked into the maze and managed to chain the Minotaur. (PROSE: Mythical Monsters)
However, the Minotaur was back in the Labyrinth by the time of his death. Athenian prince Theseus insisted on going as one of the men, and helped by Ariadne - the daughter of King Minos - he slew the Minotaur. (PROSE: A History of Humankind) The Fourth Doctor claimed to have given Theseus the ball of string that he used to find his way around the labyrinth in which the Minotaur resided. (TV: The Creature from the Pit)
The Second Doctor and The Minotaur's story became a famous myth of the Greeks and Romans. (PROSE: Mythical Monsters) Indeed, prior to meeting the Minotaur in person in his next incarnation, (TV: The Time Monster) the Second Doctor believed the Minotaur to be a fictional character. When he and Zoe Heriot encountered a simulacrum of the Minotaur in the Land of Fiction, they forced it to vanish by denying its existence. (TV: The Mind Robber)
The Eighth Doctor, Charley Pollard and C'rizz encountered an illusory Minotaur on Caerdroia. (AUDIO: Caerdroia) By the time of the War in Heaven, the Great Houses' labyrinthine records library had sprouted a Minotaur librarian calling himself Mr Smith. He knew of the original myth, and highlighted that "the Minotaur" was a lone figure, not a species. (AUDIO: A Labyrinth of Histories)