First Children. The dedicated pilot of EVA-00. A young girl who apparently lacks emotions.

Her personality makes it difficult to make new friends and she is alone most of the time. She pilots EVA-00 following all orders given by Gendou without question. Gendou seems to be like a father for her and only when being with him Rei acts like a "normal" girl. Furthermore she seems to have some feelings for Shinji as she rescues him more than once in critical situations.

Her body was actually salvaged from what was left behind of Yui's body inside EVA, and a lot of body copies were later prepared in the Terminal Dogma so that when one Rei dies she could be replaced by another.

The present Rei is the third one. The first was killed by Dr.Akagi Naoko; the second was killed in her battle against the 16th Angel. Although the personalities of these 3 Rei are different from each other, this is due to the environment. Their soul is one and the same. Also, it seems that this soul was somehow derived from Lilith.

At the final stage of the Complementation Program, she betrayed Gendou, returned to Lilith out of her own judgement and handed the future to Gendou's son -- Ikari Shinji.