In the late 1970s, his namesake and friend, Stieg Larsson, né Stig, the well-known author of the Millennium series, changed slightly the spelling of his first name to avoid confusion with Stig, by then a well-known writer.

"[5] He has published over 20 books including novels, short stories, and poetry collections.

He has also written and directed internationally successful stage plays such as Vd and Systrar, bröder.

[6] In 1989, he wrote and directed his feature film debut Ängel, followed by The Rabbit Man in 1990.

[6] He has directed TV movies such as Under isen (1991) and Nigger (1991),[6] and written screenplays for films such as Kristian Petris's acclaimed Sommaren (1995).