Question: "Who is the angel of the Lord?"
Answer: The precise identity of the "angel of the Lord" is not specifically given in the Bible. However, there are many important "clues" to his identity. There are Old and New Testament references to “angels of the Lord,” “an angel of the Lord,” and “THE angel of the Lord.” It seems when the definite article the is used, it is specifying a unique being, separate from the other angels. The angel of the Lord speaks as God, identifies Himself with God, and exercises the responsibilities of God (Genesis 16:7-12; 21: 17-18; 22:11-18; Exodus 3:2; Judges 2:1-4; 5:23; 6:11-24; 13:3-22; 2 Samuel 24:16; Zechariah 1:12; 3:1; 12:8). In several of these appearances, those who saw the angel of the Lord feared for their lives because they had "seen the Lord." Therefore, it is clear that in at least some instances, the angel of the Lord is a theophany, an appearance of God in physical form.
The appearances of the angel of the Lord cease after the incarnation of Christ. Angels are mentioned numerous times in the New Testament, but “THE angel of the Lord” is never mentioned in the New Testament. It is possible that appearances of the angel of the Lord were manifestations of Jesus before His incarnation. Jesus declared Himself to be existent “before Abraham” (John 8:58), so it is logical that He would be active and manifest in the world. Whatever the case, whether the angel of the Lord was a pre-incarnate appearance of Christ (Christophany), or an appearance of God the Father (theophany), it is highly likely that the phrase “the angel of the Lord” identifies a physical appearance of God.