Minotaur (The God Complex)

One member of a species known as Minotaurs had set itself up as a deity. When its subjects overthrew it, they sealed it aboard a prison ship which pulled in people for it to feed on. As the aeons went by, the creature lost its desire to live. It was still unable to die because the ship was programmed to provide it with a constant food supply, and its instincts were too strong to starve itself. The Eleventh Doctor, Amy Pond and Rory Williams encountered this creature, along with several other life forms collected for its next meal. Initially believing the creature fed on the fear of its victims, the Doctor cautioned everyone to avoid the rooms holding their fears and to fight against those fears by holding fast to their beliefs. Only Rory was unaffected by the creature because he did not strongly believe in anything. When Amy let go of her faith in the Doctor, the food supply was cut off and the Minotaur died. (TV: The God Complex)

Behind the scenes
This character was credited as "The Creature". In dialogue, Amy asked if it was "[a] Minotaur, or an alien, or an alien Minotaur", to which the Eleventh Doctor responded, "both".