'O God' in the Bible

Then Gideon said to God, If you are going to give Israel salvation by my hand, as you have said,

Then Gideon said to God, Do not be moved to wrath against me if I say only this: let me make one more test with the wool; let the wool now be dry, while the earth is covered with dew.

But the olive-tree said to them, Am I to give up my wealth of oil, by which men give honour to God, and go waving over the trees?

For you are with child and will give birth to a son; his hair is never to be cut, for the child is to be separate to God from his birth; and he will take up the work of freeing Israel from the hands of the Philistines.

But he said to me, You are with child and will give birth to a son; and now do not take any wine or strong drink or let anything unclean be your food; for the child will be separate to God from his birth to the day of his death.

And opening all his heart to her, he said to her, My head has never been touched by a blade, for I have been separate to God from the day of my birth: if my hair is cut off, then my strength will go from me and I will become feeble, and will be like any other man.

And Samson, crying out to the Lord, said, O Lord God, do have me now in mind, and do make me strong only this once, O God, so that I may take one last payment from the Philistines for my two eyes.