Larsson started out as a political activist for the Kommunistiska Arbetareförbundet (Communist Workers League), as well as a photographer, and proclaimed himself one of Sweden's leading science fiction fans.

Unable to avoid all confusion, the pronunciation of both versions is the same regardless of spelling. Stieg, in later years, would tell the story that the two men had tossed a coin to decide who was to change his name, but this account is disputed by Stig Larsson. At this point, neither had yet to published a book, but they wished to avoid confusion as they were working in the same field. At the time, the two friends were amateur photographers and with such similar names, they wished to prevent any misunderstanding. Larsson's first name was actually Stig which is the standard spelling, however in his early twenties, he changed it to avoid confusion with his friend Stig Larsson, who went on to become a famous author many years before Stieg did.

Four years after his death, he was the second best-selling author in the world in 2008, behind Khaled Hosseini, and by March 2010, his Millennium trilogy had sold over 27 million copies in more than 40 different countries. He is best known for writing the Millennium Trilogy of crime novels, which was published posthumously. Karl Stig-Erland Larsson (known to the world as author Stieg Larsson) was a Swedish journalist and writer, born Augin Skelleftehamn outside Skellefteå in Sweden.

The millennium series by stieg larsson