Rei Ayanami is the first child to be selected by the Marduk Institute. All records about her have been erased. Therefore, nobody knows where she came from, who her parents are/were, or who she is. She is a very quiet girl and can't express her feelings to other people very well, much like Shinji. It seems like only Commander Ikari can communicate with her and she only shows her smile to him. She lives in a small noisy flat which is messy. She seems to be a vegetarian.

Rei is a human who poses Angel like abilities. She is a clone of Yui Ikari and has multiple "backup" bodies in Central Dogma. She was artificially made in the beginning for Gendou's Human Instrumentality Project. It seems that it is possible to transfer her "real" soul to another body in the event of her death. She is said to process some Angel like characteristics. She has red eyes, same as Kowaru Nagisa, and she can also generate a very strong A.T Field.