Steven Moffat is a master of taking everyday fears and turning them into monsters from the very depths of the nightmarish, and nothing is a better example of this than the Vashta Nerada. There's a reason to be scared of the dark, because it can eat people. Then it can use their skeleton and spacesuit to chase others, and cling onto them by pretending to be a second shadow. Seriously. Not cool, guys. Though they caused hundreds of Whovians to check that they only had the one shadow, the concept isn't the only effective thing about the Vashta Nerada. The design of the shadow in the suit is creepy enough to live up the the aliens' billing, and their tweaked appearance in the Adventure Games suggests that there could be a lot of room for further inventiveness if they were to ever appear again. And there's been a lot of fan clamour for that return. Of course, a future episode could take place on Earth. Apparently, there are small pockets of the Vashta Nerada all over the universe, including our own home planet. Because Moffat didn't want to risk anyone sleeping easily, did he?
