The Minotaur a mythical creature
The Minotaur is just a legend but the Minotaur did appear in 2 adventures.
We first saw one in the 2nd Doctor story "The Mind Robber" when one chased the Doctor and Zoe in the tunnels.
More recently one did appear in an episode in Series 6 Part 2. This Minotaur guarded an 80s hotel which people and creatures vanished inside. Each of the hotel rooms has a scare for everbody like in some of the rooms there were a Clown and a couple of Weeping Angels. The Minotaur took those people and made them die. The hotel was actually a prison spaceship for the Minotaur but it was disguised as an 80s hotel. The Minotaur died in the end and the Doctor was sorry.
The Minotaur has appeared in
2nd Doctor Season 6: The Mind Robber
Series 6 Part 2: The God Complex