19. "YOU CAN'T MEND PEOPLE!" (Kinda)
It might have an unconvincing pink snake, half the cast of The Bill, and a very fake looking forest, but Kinda is genuinely terrifying. Not in a jump scare sort of way, but in a psychological way that can really get under your skin and freak you out.
The Fifth Doctor regularly seems out of his depth here, not knowing how to deal with the increasingly unpredictable Hindle and disarm the explosive devices set around the Dome.
In this memorable scene, the Doctor returns to the Dome to find Hindle and Sanders building a model village. When the Doctor accidentally breaks the head off one of the model villagers, Hindle memorably screams "YOU CAN'T MEND PEOPLE CAN YOU?" while waving the decapitated cardboard figure in the Doctor's face.
It's one of the most genuinely spine-chilling portrayals of madness in the show's history.