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.

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.

Lisbeth Salander's court-appointed guardian after Holger Palmgren's stroke. A lawyer who abuses his position of power.

Director of Milton Security, a private security firm. Lisbeth Salander's employer and one of the few people she considers an ally. Has a protective, quasi-paternal relationship with Salander. Of Armenian origin, based in Stockholm.

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.

Elderly patriarch of the Vanger industrial dynasty. Obsessed for four decades with the disappearance of his great-niece Harriet from Hedeby Island in 1966. Hires Mikael Blomkvist to investigate, offering damaging evidence against Wennerstrom as payment.

Lisbeth Salander's first court-appointed guardian and the closest thing she has to a father figure. A retired lawyer who genuinely cared for her and fought to protect her rights. Suffered a stroke and was replaced by Bjurman. Recovers slowly and returns in the third book to lead her legal defence.

Blomkvist's sister, a lawyer specialising in family law and women's rights.

Henrik's niece, a school teacher and daughter of Harald Vanger, with whom Blomkvist has a brief affair.

Art director and part-owner of Millennium magazine.

Henrik Vanger's elderly lawyer who recruits Blomkvist for the Harriet investigation.

Retired detective superintendent who investigated Harriet Vanger's disappearance and became obsessed with the case of the pressed flowers.

Swedish billionaire financier and stock-market speculator who sued Blomkvist for libel and is later exposed as a criminal.

Henrik's ninety-two-year-old brother, a reclusive former doctor with a Nazi past.

Henrik Vanger's grandniece who disappeared in 1966 and was believed dead, but is later found alive in Australia.

Harriet and Martin's mother, a vain and irresponsible woman of German origin.

Managing editor of Millennium who is suspected of being disloyal and leaking information.

CEO of the Vanger Corporation and Harriet's brother, who is revealed to be a serial killer continuing his father's legacy.