10 Best One-Time Only Doctor Who Villains
7. The Minotaur (The God Complex)
Just as the Gelth would've been uninteresting spectres if not for some clever writing that linked them to the Time War and gave them a compelling backstory, the Minotaur from Series 6 would've been nothing more than a towering brute if it wasn't given a complex reason for its evil-doing, and injected with a bit of pathos.
In The God Complex, the Doctor, Amy and Rory land in what seems to be an ordinary Earth hotel, but is actually a maze-like structure patrolled by the mythical Minotaur.
For the vast majority of the episode, the Minotaur just seems like a mindless beast (although we do get hints that it's suffering in some way) but eventually, we learn that it doesn't really want to hurt people and that it just wants to die, a wish that is finally granted when the Doctor, in an emotional scene, severs its food supply.
With a terrific, fully-practical costume - one that actually allows the creature to express itself when required - and the surprisingly saddening twist that the Minotaur is actually a victim trapped within the walls of the hotel, this is a villain that has it all: incredible design combined with incredible execution.