Note: All you really see of this angel is red since it's basically a virus, so the red part(circled in blue)is the actual angel
This angel was basically a virus, invading NERV's computers, and eventually the Magi. It was stopped when Rituko raced against the angel to overcome the last Magi, Casper, after both Melchiore and Balthasar were taken over. Ritsuko uploaded an auto-selfdestruct sequence, which the angel also programmed into itself, and was destroyed.