'Angel of the Lord' in the Bible

and when he was thinking on these things, behold an angel of the Lord appeared to him in a dream, saying, Joseph thou Son of David, scruple not to take unto thee Mary thy wife; for that which is conceived in her is from the Holy Spirit.

So Joseph, when he awoke from his sleep, did as the angel of the Lord directed him, and took home his wife:

And when they were departed, behold an angel of the Lord appeareth to Joseph in a dream, saying, Rise and take the child and his mother, and flee into Egypt, and continue there, untill I tell thee to return: for Herod will seek the child to destroy Him.

But when Herod was dead, behold, an angel of the Lord appeareth in a dream to Joseph in Egypt,

and behold, there had been a great earthquake; for an angel of the Lord descending from heaven, had come and rolled away the stone from the door, and was sitting upon it: