Riddles about darkness

It can't be seen, can't be felt, can't be heard and can't be smelt. It lies behind stars and under hills, and empty holes it fills. It comes first and follows after, ends life and kills laughter. What is it?

When you have me more, you can see only less. What Am I?

I can fly but I have no wings. I can cry but I have no eyes. Wherever I go, darkness follows me. What am I?

The more you have of it, the less you see. What is it?