EVA-00

Japanese name:

零号機

Eva-00 was the first operational Evangelion. Being a prototype, it was not originally equipped for combat, but was later upgraded and brought into battle against the Angels.

As is the case for all the Evangelions, except Eva-01, the method of Eva-00's creation is not known. It is known, however, that she was the first working prototype after many failures. Whether the creation process was perfected with Eva-00, or if something new was tried would be pure conjecture.
What is known is that the original design for the prototype Eva had been created a long time ago; Fuyutsuki sees a mockup of Eva-00 in 2003, with the same orange and white color combination and the same head design. We also learn here that Eva-00 would have had a cluster of five cameras beneath its single eye lens.
Eva-00 is the most unstable of the Evangelions, going wildly berserk one two occasions; once during its activation experiment with Rei, and again during its interchangeability experiment with Shinji. Despite these incidents Rei retains good control over the Eva once it is operational, using it successfully in quite sensitive tasks such as handling the Lance of Longinus on two occasions and both fetching and firing the SDF's positron cannon.

The Eva's face has never been revealed on-screen, being covered by the helmet and faceplate at all times. Unique to Eva-00 is the large optical lens on its faceplate. In addition, the faceplate lacks nostril holes or a proper jawline. Monitor readouts of the Evangelion's internal organs reveal that it actually has two eyes as well as nostrils and a jawline. The design of the helmet suggests that Eva-00's skull might be somewhat narrower than those of other Evangelions.
Eva-00 originally had orange armor and a different arrangement of plates from Eva-01 and the Production Model Evangelions, also, when first seen it does not have shoulder pylons attached. After sustaining severe damage from the Angel Ramiel, Eva-00 was refitted with the same armour design as the Production Model Evangelions; Shoulder pylons were added, the armour plating was altered, and the colour scheme changed from the original orange to blue. The repaired Eva-00 is also seen to possess retro-rockets in her shoulder pylons in Episode 11, as well as a Progressive Knife, seen in Episode 12.
An early Eva-00 design seen in the Proposal has a head design identical to that used in the show. In addition, the blue color scheme is very similar to that used in the repaired Eva-00.

The identity of the soul contained in Eva-00 is never directly stated, but analysis of various clues and hints dropped through the series points to it being the soul of Rei 1, the first Rei Ayanami clone(or a part thereof).
For more in-depth analysis, see "Eva-00's soul"

Evangelion Unit-00 has seen less action than the Test Type Eva-01 and the Production Model Eva-02, and largely in an auxiliary role until the end. The Eva was occasionally used to transport critical equipment; one example was when it carried parts for the positron rifle in Episode 05 and the Spear of Longinus at the end of Episode 14.
Although Eva-00 was the first working Evangelion out of a very long line of failed prototypes, it was not the first Evangelion to engage in combat with an Angel. That honor belongs to Eva-01. Eva-00 went berserk during an activation test 21 days before the Third Angel, Sachiel, arrived. During the incident the entry plug was ejected, possibly by the Eva itself, resulting in serious injuries to the pilot, Rei Ayanami.
Following a successful activation test, Eva-00 went into battle against the Angel Ramiel in a critical support role, using a heat shield from an SSTO spacecraft to shield Eva-01 from the Angel's deadly particle beam. The Eva suffered severe thermal damage and had to undergo extensive repairs, including a complete replacement of the original orange armor by a new set of blue armor. Eva-00's new armor fit is identical to those used on Production Model Evangelions, including pylons.
Eva-00 saw combat again with the Ninth Angel, Matarael, although as a backup player. It again went into combat against the Tenth Angel, Sahaquiel, stopping it from overwhelming Eva-01 and opening its A.T. Field for Eva-02 to strike the fatal blow. The battle against the Angel Bardiel resulted in the loss it's left arm. Unit-00 suffered critical skull damage during the battle against the Angel Zeruel.
The Eva finally got center stage during the battle against the orbital Angel Arael, throwing the original Spear of Longinus to destroy the Angel. Unit-00 was lost in the battle with the Angel Armisael, during which it self destructed to destroy the Angel.

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