Katsuragi Misato

Lieutenant Katsuragi, later promoted to Major, is NERV's Operations Chief.
Misato is a direct survivor of Second Impact, as she was in the Antarctic with an expedition of her father when Adam was first discovered.
She was picked up in a rescue-pod her father put her in after several days on the ocean, her only belongings were her clothes and a silver cross her father gave her. Misato was traumatized and didn't speak for several years, but after that seemingly unstoppable ;-)
She became friend with Ritsuko in university, where she also met her one, true love Ryohji, whom she left but still loves.
Misato is a gorgeous and sensual young woman, and in contrast to her discipline on-duty, she regularly drinks too much off-duty, her flat is sloppy and her favourite hobby at university seemed to be sex.
Misato becomes Shinji's and later Asuka's caretaker, and it seems that this little "family" is something she embraces, though it becomes also clear that she is willing to sacrifice her protégé's for the cause (because she hates the angels from deep within).