'Angel of the Lord' in the Bible

But the angel of the Lord said to Elijah the Tishbite, “Arise, go up to meet the messengers of the king of Samaria and say to them, ‘Is it because there is no God in Israel that you are going to inquire of Baal-zebub, the god of Ekron?’

The angel of the Lord said to Elijah, “Go down with him; do not be afraid of him.” So he arose and went down with him to the king.

Then it happened that night that the angel of the Lord went out and struck 185,000 in the camp of the Assyrians; and when men rose early in the morning, behold, all of them were dead.