'Mighty Angel' in the Bible

and I saw a mighty angel proclaiming with a loud voice, Who is worthy to open the book and to loose the seals of it?

And I saw another mighty angel coming down from heaven invested with a cloud: and there was a rainbow on his head, and his face was as the sun, and his feet as pillars of fire.

And a mighty angel took up a stone like a great milstone, and cast it into the sea, saying, Thus shall the great city Babylon be thrown down with violence, and never be found more.