'Angel of the Lord' in the Bible

But an angel of the Lord opened the doors of the jail during the night, brought them out, and said,

An angel of the Lord spoke to Philip: “Get up and go south to the road that goes down from Jerusalem to Gaza.” (This is the desert road.)

Suddenly an angel of the Lord appeared, and a light shone in the cell. Striking Peter on the side, he woke him up and said, “Quick, get up!” Then the chains fell off his wrists.

At once an angel of the Lord struck him because he did not give the glory to God, and he became infected with worms and died.