Doctor Who: 10 Scariest Episodes That Sent Us All Behind The Sofa

7. The Waters Of Mars

'The Waters of Mars' makes for a fascinating parallel with 'Pond Life', funnily enough. During the Eleventh Doctor's alone time, he ran around the universe having fun, even recording a rap song at one point. Ten however, just became insane with power (feel free to make any Kanye West jokes you feel appropriate). 'The Waters Of Mars' was easily the darkest moment yet for the Tenth Doctor, as he became livid with always losing his friends, declaring himself the "victor" of his extinct race. Russell T Davies turned in an extremely adult script; this was a base on Mars that became infected with a vicious disease, from which no one could escape. Human beings became cracked monsters, vessels for what seemed like an ancient and evil parasite. This was probably what drove the Ice Warriors away from Mars. This was a very real, and ever-growing threat. That threat became just a footnote in the "Dark David Tennant Story". Whether or not anyone actually remembers just how scary the water was though - despite how scary Ten became - it really was one of the most frightening episodes of Davies's tenure.