9. 42 (Series 3)
Here is Series 3's worst episode. This episode contained a villain that can only be compared to a wasted idea. The episode alone felt rather rushed due to the fact that the Doctor had to save Martha Jones and the ship's crew within 42 minutes. Compared to this, Series 5's The Eleventh Hour has a steady pace. What's more, this particular episode has no significant components relating to the overriding plot of the whole series and it's an exhausted idea which should have been thoroughly thought through. Making a better episode of this would be to have a less rushed story and there should have been more of a dynamic between the Doctor and Martha.