Eva Unit 00
EVA-00 is the first Eva to be constructed, and is piloted by Rei Ayanami; the first child.  In order for the prototype to be a viable option for close combat against Angels, NERV upgrade the Eva shortly after the eighth Angel is destroyed.  Unit 00 has also been known to run amok on a couple of occasions.  It was initially thought to have been caused by mental instability from within the pilot, however, it is later determined that the instability originated from within the actual Eva.  It's highly likely that Unit 00's core was in fact built from the soul of Rei Ayanami.
Model: Prototype
Number: 00