Ramiel

Ramiel is an "angel of thunder", his name means "Mercy of God".
One of the holy angels, whom God set over those who rise.
In the series, Ramiel appears as a large, blue "grain of salt" (episode 5), a flying fortress that entered Tokyo-3's airspace and started drilling through the GeoFront's armament from above.
Because of his extremely powerful AT-field and a very strong energy weapon, he couldn't be defeated in close combat. So NERV had to "borrow" a positron-rifle from the JSSDF and juiced it with all the power that Japan could deliver.
Ramiel was finally defeated in a long-range shootout, but Rei in Unit-00 was injured, because she stepped in the way of Ramiels fire to protect Shinji, who operated the rifle. After that, Unit-00 was refited, now with the blue armament and combat-gear (before it was equiped with an orange prototype-outfit).