Description from original post (created 2012-03-23 15:21):
The Silent from Dr.Who.
The Silence are a terrifying race who invaded Earth at an undetermined point in our history. They have powers of telepathy and can kill using a deadly discharge from their hands. But every Silent has a far eerier ability...
Even if you see a Silent, you won't know you've spotted it as Silence somehow edit themselves from an observer's memory. Glimpse one of these creatures and you may feel slightly unsettled the moment it's out of view, but you won't remember anything about it. If and when you next see a Silent you may have a flashback to your first encounter, but again, when the Silent is out of view your mind will not recall ever seeing the alien.