8. The Rutan Host
For those of you who find mold frightening, better reserve a spot behind the couch -- the Rutan are coming to town. These guys are the sworn enemies of the Sontarans, but are only seen once on Doctor Who. After their reveal in Horror of Fang Rock, it's easy to see why. At their scariest, they're just kind of gross looking. They remind me of those sticky toys that are fun for about an hour, and then quickly become disgusting after they're immediately covered in dust, cat hair, and dead skin cells. I genuinely do not understand how these little green blobs are a legitimate threat to anything.