A "Silent" from Doctor Who. For those that don't know them, these are the big bads that are the running undercurrent of the 11th Doctor's era. They are memory-proof... meaning that once you look away from them, you forget you ever saw them. And if they tell you something when you're looking at them, you'll subconsciously obey the instruction whilst never knowing you weren't coming up with it on your own.
These guys are seriously freaky... and all to keep the first question from ever being answered.
You'll love this picture... but you'll never remember why.