Rei 2

"Rei 2" is the second Rei Ayanami clone, actually the first encountered during the series, in Episode 01. Rei 2 is the personification of "Rei Ayanami" seen during almost all of the series, from Episode 01 through the middle of Episode 23 when she sacrifices herself and her Evangelion Unit-00 in order to destroy the Angel Armisael.

While Rei 1 may have been a potential Eva pilot had she lived, and Rei 3 was still considered a backup pilot after Eva Unit 00 was destroyed, Rei 2 was the only "Rei" clone to actually pilot an Eva.

Notes

• "Rei 2" is a fan-created designation, sometimes written as "Rei II".
• It is very probable that part of the soul of "Rei Ayanami" (actually, the soul of the Angel Lilith) from Rei 1 was used as the soul inside of Eva Unit 00. This may explain the difference in personality between Rei 1 and Rei 2, as Rei 2 was "missing" parts of her soul/personality. This might explain why Rei 2 is incredibly withdrawn, and the other two Rei clones were relatively more open. For further analysis, see: "The Soul in Evangelion Unit-00".