'Angel of the Lord' in the Bible

And they answered the angel of the LORD that stood among the myrtle trees, and said, We have walked to and fro through the earth, and, behold, all the earth sitteth still, and is at rest.

Then the angel of the LORD answered and said, O LORD of hosts, how long wilt thou not have mercy on Jerusalem and on the cities of Judah, against which thou hast had indignation these threescore and ten years?

And he shewed me Joshua the high priest standing before the angel of the LORD, and Satan standing at his right hand to resist him.

And I said, Let them set a fair mitre upon his head. So they set a fair mitre upon his head, and clothed him with garments. And the angel of the LORD stood by.

And the angel of the LORD protested unto Joshua, saying,

In that day shall the LORD defend the inhabitants of Jerusalem; and he that is feeble among them at that day shall be as David; and the house of David shall be as God, as the angel of the LORD before them.