Gaghiel

Gaghiel is described as "angel of fish" or a guardian of the sixth heaven.
So it is not astounding, that Gaghiel appears (episode 8) as a giant underwater-creature. Evangelion Unit-02 is transported from Germany to Tokyo-3 by an aircraft-carrier. Gaghiel destroys most of the escorting UN-ship.
Asuka, desperate to prove her status as a warrior (and to show off in front of Shinji, whom she takes with her into the entry-plug), attacks Gaghiel with Unit-02 and is thrown over board.
The following underwater battle isn't really fair, as Unit-02 still is carrying the "B"-equipment. But Gaghiel is finally destroyed, when Misato sinks two remaining cruisers right into Gaghiels opened mouth (with Unit­02 as a toothpick).
The ships explode, and so does Gaghiel.