Misato Katsuragi is the chief operations officer at NERV, initially holding the rank of Captain (with a later promotion to Major). She is the field commander for the Eva pilots, issuing orders and giving battle strategies. She also acts as Shinji and Asuka's guardian, letting them live in her apartment rather than have them living alone.
While she is professional and diligent in her duties, she is a slob and a drunkard while off-duty. She is the only survivor of the Katsuragi Expedition, the scientific study led by her father which triggered the Second Impact; the cross pendant she wears was given to her by her father just before his death.
She and Ryoji Kaji were lovers during college, and slowly rekindle their romance over the course of the series. She was also friends with Ritsuko Akagi in college and their relationship unravels as Misato learns more about NERV and SEELE.