Weeping Angels are by far the most terrifying creatures in the universe. They're as old as the universe, no one really knows where the come from, and they were once called the lonely assassins. The first episode they appear in is during Series 3, the same episode where we learn that time is actually a big ball of wibbly wobbly timey wimey ... stuff.
The Doctor explains Weeping Angels much better.
Pictured here is three coats of NerdLacquer Don't Blink. It's a stone grey polish littered with pieces of white and grey glitter giving it the same appearance as a Weeping Angel.