Matariel

Matariel is one of the rulers of this world, an "angel of rain".
His appearance is (episode 11) a giant - but weak - spider. He attacks the Geo-Front with an acid-rain(!) he spits on them. Where the acid hits the ground, it starts melting anything. Unfortunately, Nerv experiences a power-loss right before the angel-attack, so the Units 00,01and 02 have to be started using Diesel-engines and batteries.
They finally defeat Matariel together from below. After climbing up a "narrow" (at least for the Evangelions) shaft - and loosing a heavy rifle (aargh) - they work as a team. Rei shields the other two from the acidic fluids, while Asuka jumps down the shaft to get the rifle. She throws it up to Shinji, who then kills Matariel.