Warning possible spoilers ahead (if you haven't already been spoiled by the writeup above).
The
First Children, and dedicated pilot of
Eva-00. A
young girl who apparently lacks
emotions. Her body was created from the salvaged remains of
Yui Ikari after Yui was taken into the
Eva, and numerous Rei clones were then prepared in
Terminal Dogma so that when one
Rei dies she can be replaced by another. The present Rei is the
third. The
first was
killed by Dr.
Naoko Akagi, and the
second died in battle against the 16th
Angel. Although the personalities of these three Reis differ from one another, this is due to
environmental factors. Their
soul is one and the same, and it appears to have been that of
Lilith. At the final stage of the
Instrumentality Project, Rei betrayed
Gendou Ikari, returned to
Lilith of her own judgment and entrusted the future to Gendou's son -
Shinji Ikari. Birth date:
unknown.
Source: The End of Evangelion : Glossary contained within The End of Evangelion - Theatrical Program.