Fourteen years of research and billions of dollars have been spent to create the "All-purpose Humanoid Fighting Machine - Evangelion."Constructed in secret and controlled by Special Agency NERV, these massive biological machines were ostensibly created to defend the Earth from theinvading Angels. They can only be piloted by 14 year olds who've lost their mothers. Their name is derived from "Eve" - wife of Adam in the Old Testament, and "Evangel," meaning "gospel."
Piloted by Rei Ayanami, Eva-00 was the first success for the Gehirn Research committee after many failures. During it's initial activation with Rei as Pilot, Eva-00 went berserk, broke loose from its anchors, and in explicably attempted to smash through to the observation area window. Rei was severely injured during the incident. The Eva was frozen with Bakelite and later salvaged. Although initially orange in color, Unit-00's plating was replaced with blue and white armor after heavy damage sustained during the 5th Angel's attack.
Unit-01 was the first Eva to be used in combat against the Angel's. Piloted by Shinji Ikari, Unit-01's body was created from Lilith and is inhabited by the soul of Shinji's mother, Yui Ikari - facts that may explain the Eva's occasional unusual behavior such as activating without an entry plug, going berserk, and remaining active after its operational time limit had expired. The Eva is also the first to possess an S^2 engine, which it gained by devouring the 14th Angel Zeruel. Because of its unique constitution, Eva-01 became the sole substitute for Lilith as the medium for achieving Human Instrumentality once the Lance of Loginus had been lost.
Fiery red in color, perhaps to match the temperament of its dedicated pilot - Asuka Langely, Eva Unit-02 was the first production model built on the assumption of actual combat. Though designed and manufactured in Japan, Unit-02 was assembled in Germany. It first faced combat against the 6th Angel when attacked at sea during its transport back to Japan. The soul of Asuka's mother, Sohryu Kyouko Zeppelin, resides inside Eva-02.
Constructed at the 1st U.S.NERV facility, this dark blue production model Eva was infected by the Thirteenth Angel while being transported by air to Japan. During activation tests near Matsushiro, the Angel took control of Unit-03 and was destroyed by Eva Unit-01. The pilot and Fourth Child, Touji Suzuhara, who was in the entry plug at the time lost part of his leg, but survived the incident.
Constructed at the NERV-2 base in Nevada, this production model Eva was created for the sake of developing and analyzing both the S^2 engine, believed to have been transplanted from the remains of the Fourth Angel, and the Dummy Plug system. Upon activation of the engine, both Unit-04 and the NERV-2 base dissapeared- apparently into a pocket universe called a "Sea of Dirac."
The nine Evangelion mass-production Units were built outside of NERV Headquarters and share a common configuration and coloring. Because they utilize the Dummy Plug system, they are under the direct control of SEELE. their Dummy Plugs all bear the name "Kaworu," so appear to have been created using the thought patterns of the 17th Angel. All possess S^2 engines and are armed with facsimiles of the Lance of Longinus.