Answer:
I am a rock group with four members. All dead one was assassinated.
I may seem real but it always turns out I was never there in the first place... you only see me during a certain resting stage.
Four leaves I have.
I sit high glowing and watch the world go by. Without me everything would seem dull and dangerous. What am I?
The more of me there is the less you see.
I am your mother's brother's only brother in law. Who am I?