'O God' in the Bible

And have cast their gods into the fire: for they were no gods, but the work of men's hands, wood and stone: therefore they have destroyed them.

You are my witnesses, says the LORD, and my servant whom I have chosen: that you may know and believe me, and understand that I am he: before me there was no God formed, neither shall there be after me.

Thus says the LORD the King of Israel, and his redeemer the LORD of hosts; I am the first, and I am the last; and besides me there is no God.

Fear not, neither be afraid: have not I told you from that time, and have declared it? you are even my witnesses. Is there a God besides me? yea, there is no God; I know not any.

I am the LORD, and there is none else, there is no God besides me: I girded you, though you have not known me:

Verily you are a God that hides yourself, O God of Israel, the Savior.

For since the beginning of the world men have not heard, nor perceived by the ear, neither has the eye seen, O God, besides you, what he has prepared for him that waits for him.