Answer:
I can be hairy and itchy all over. I hang on a stick. I can be the scariest thing you have ever seen. I stand in the middle of nowhere.
I'm as simple as a circle worthless as a leader; but when I follow a group their strength increases tenfold. By myself I'm practically nothing.
I am a cave full of bones and the house of a worm.
I make you weak at the worst of all times. I keep you safe, I keep you fine. I make your hands sweat and your heart grow cold. I visit the weak, but seldom the bold. What am I?
I don't live within a house nor do I live without. Most will use me when they come in and again when they go out.
What language does a billboard speak?