5) The Impossible Planet/The Satan Pit
It is my firm belief that the writers for this episode ran out of ideas for new and terrifying villains for this episode, until Matt Jones said “Guys! Let’s have him fight The Devil!”. Regardless, it worked, and it ended up being one of the best, and certainly one of the most intense and terrifying episodes of the show. The level of fear in this story is close to that of Blink; the Possessed Ood had me and my younger brother (I was 8 and he was 5) petrified for weeks. It showed that while it may be intended for a young audience, Doctor Who has no problem with embracing dark stories, and tackling on huge villains like the freakin Devil!