'Angel of the Lord' in the Bible

But during the night an angel of the Lord opened the gates of the prison, and taking them out he said,

But an angel of the Lord spoke to Philip saying, “Get up and go south to the road that descends from Jerusalem to Gaza.” (This is a desert road.)

And behold, an angel of the Lord suddenly appeared and a light shone in the cell; and he struck Peter’s side and woke him up, saying, “Get up quickly.” And his chains fell off his hands.

And immediately an angel of the Lord struck him because he did not give God the glory, and he was eaten by worms and died.