An unnamed angel appeared at the empty tomb that first Easter morning. This icon is a study of a larger piece, which includes the sleeping soldiers, and the women, coming to care for Jesus' body.
You'll notice that the perspective on the "stone" is all wrong, not aligned with some focal point in the distance at which all lines merge into one, as we learned in art class in elementary school (I still remember drawing roads that disappeared off into the sunset, flanked by similarly shrinking telephone poles or trees...). Perspective in iconography is "reversed," with things often getting larger as they move away from the viewer, symbolizing the ever-expanding nature of the Reign of God. The consequence of this perspective is also that the viewer is that infinitessimally small vanishing point. Rather keeps things in, well, perspective.