Larsson completed three books before his death; David Lagercrantz penned the next three; and Karin Smirnoff is in the midst of writing the third trilogy.

The two primary characters in the saga are Lisbeth Salander, an asocial computer hacker with a photographic memory, and Mikael Blomkvist, an investigative journalist and publisher of a magazine called Millennium.

In 2013, Norstedts Förlag commissioned Swedish author David Lagercrantz to continue the Millennium series with Larsson's characters.

In November 2021, publishing house Polaris acquired the rights to the series from Larsson's estate and announced a new trilogy of books written by Swedish author Karin Smirnoff.

To Larsson, there was no difference, and the "systemic violence" against women highly affected and inspired him to take action against these crimes through his writing.

Eva Gabrielsson, Larsson's longtime partner, wrote that "the trilogy allowed Stieg to denounce everyone he loathed for their cowardice, their irresponsibility, and their opportunism: Couch potato activists, sunny-day warriors, fair-weather skippers who pick and choose their causes; false friends who used him to advance their own careers; unscrupulous company heads and shareholders who wrangle themselves huge bonuses... Seen in this light, Stieg couldn't have had any better therapy for what ailed his soul than writing his novels.

As an example, she said he used her unfinished book about architect Per Olof Hallman to research locations for the Millennium series, and that the two of them physically checked places together and discussed where the characters would live.

"[1] MacLehose explained that the translations were commissioned by the Swedish company who adapted the books to film in order to aid an English-speaking screenwriter whom the producers were hoping to hire.

[26] Smirnoff said she accepted the offer without hesitation and stated "The Millennium books are classics in their genre, where the combination of unforgettable characters and the strong political and societal engagement still fascinates readers.

I will continue to build on Stieg Larsson's core themes, such as violence, abuse of power, and contemporary political currents.

[1] In 2010, Larsson's friend John-Henri Holmberg showed Associated Press emails he received from the author shortly before his death that supposedly described plans for another book in the series.

In them Larsson wrote, "The plot is set 120 kilometers north of Sachs Harbour, at Banks Island in the month of September ...

"[28] Gabrielsson has described the manuscript in her possession as roughly 200 pages, having a working title of Guds hämnd (God's Revenge),[29] being 30% complete and "Not worth publishing as is."

He described the manuscript as being the fifth in the series, set "between Ireland, Sweden and the US" and largely featuring Lisbeth Salander's twin sister Camilla.

[33] In July 2010 the series made Larsson the first author to sell a million electronic copies of his work on the Amazon Kindle.

The first film was directed by Niels Arden Oplev and the next two by Daniel Alfredson, while the screenplays of the first two were adapted by Nikolaj Arcel and Rasmus Heisterberg, and the last one by Ulf Rydberg and Jonas Frykberg.

The Girl with the Dragon Tattoo was written by Steven Zaillian, directed by David Fincher and produced by Scott Rudin, with Daniel Craig as Mikael Blomkvist and Rooney Mara as Lisbeth Salander.

The studio had hoped to have the same people involved in the sequels as in the first film, with Fincher directing and Daniel Craig and Rooney Mara starring, but scheduling has been difficult.

[43] The adaptations were written by Scottish crime novelist Denise Mina, with art by Leonardo Manco and Andrea Mutti.

For the Franco-Belgian market, a separate adaptation has been published, written by Sylvain Runberg with artwork by José Homs and Manolo Carot.

Starting in 2016, Runberg followed up the series with newer stories based on the characters, Millénium Saga, drawn by Belén Ortega, independent of David Lagercrantz' sequels.