10 Chilling Doctor Who Unsolved Mysteries

10. The Nature Of The Beast

Up until recently, Doctor Who would offer sci-fi explanations for things like ghosts and vampires. Which is what makes the mystery of the Beast so fascinating.

The Impossible Planet and The Satan Pit found the Tenth Doctor and Rose stranded on a strange planet orbiting a black hole. Unbeknownst to them, the planet is actually a prison for "the Beast", an enormous and ancient creature trapped beneath the surface.

The Beast's design is intentionally similar to the traditional depiction of Satan: red skin, horned head, generally unpleasant attitude. However, as the Doctor explains, most religions he knows of feature something that looks like this, implying that the Beast has served as the blueprint for the embodiment of evil across the universe.

But what exactly is the Beast itself? Is it the actual literal Devil, or the oldest fraud in the universe? And would a singular Devil imply the existence of a singular God? Even the Doctor himself is unsure, dismissing the Beast's claims that it existed before the universe was created.

The episode is intentionally ambiguous, which only makes this creature more unsettling. All that's certain is that the Doctor encountered an immense power in the depths of Krop Tor.