It is almost impossible to accurately label something as universally horrifying. So don't look into it too much. Just tell us what the scariest thing that you have ever seen, It can be fiction or fact. Use as much description as you wish.
Well, this is probably the most terrifying thing I have seen, fortunately, they are fiction.
http://en.wikipedia.org/wiki/Weeping_Angels#Weeping_Angels
Basically they cannot move while you are looking at them but the second you avert your gaze they move very rapidly. Granted they don't actually kill you, but be honest, your staring at a statue, you blink and then your faced with this:
http://blogs.coventrytelegraph.net/thegeekfiles/Weeping Angel 3.jpg
It's a seriously fucked up concept.
Well, this is probably the most terrifying thing I have seen, fortunately, they are fiction.
http://en.wikipedia.org/wiki/Weeping_Angels#Weeping_Angels
Basically they cannot move while you are looking at them but the second you avert your gaze they move very rapidly. Granted they don't actually kill you, but be honest, your staring at a statue, you blink and then your faced with this:
http://blogs.coventrytelegraph.net/thegeekfiles/Weeping Angel 3.jpg
It's a seriously fucked up concept.