Co-owner and publisher of Millennium magazine and an investigative journalist with a reputation for exposing financial corruption. Convicted of libel against financier Hans-Erik Wennerstrom at the opening of the first novel, he accepts Henrik Vanger's commission to investigate the disappearance of Harriet Vanger as a way to find evidence that will clear his name. Principled, persistent, and given to affairs with women he works with.

Editor-in-chief of Millennium magazine and Mikael Blomkvist's long-term lover and closest friend. Married to artist Greger Beckman in an open relationship. Calm under pressure, politically astute, and fiercely loyal to both Blomkvist and the magazine. Takes a position as editor of the newspaper SMP in the third book.

A brilliant, asocial researcher and hacker with a photographic memory and exceptional capacity for pattern recognition. Declared legally incompetent as a teenager following a confrontation with her father Zalachenko, she was institutionalised and subjected to abuse by the state. 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.