'Angel of the Lord' in the Bible

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

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

Suddenly, an angel of the Lord appeared [beside him] and a light shone in the cell. The angel struck Peter’s side and awakened him, saying, “Get up quickly!” And the chains fell off his hands.

And at once an angel of the Lord struck him down because he did not give God the glory [and instead permitted himself to be worshiped], and he was eaten by worms and died [five days later].