A brilliant, asocial researcher and hacker with a photographic memory and exceptional capacity for pattern recognition. Declared legally incompetent as a teenager after a particular incident in her early life - the events surrounding which the later books of the Millennium series unfold with deliberate, careful weight. Fiercely independent, she operates by her own moral code and does not forgive those who harm her or the vulnerable. Bisexual, heavily tattooed, and lives almost entirely off the grid by choice.