Conversation so far:
what is the order of the girl with the dragon tattoo trilogy?
The Girl with the Dragon Tattoo in 2005, The Girl Who Played with Fire in 2006, and The Girl Who Kicked the Hornets' Nest in 2007.
who was the author of The Girl with the Dragon Tattoo trilogy?
Stieg Larsson
how many were in the Millenium novel series by Stieg Larsson?
Larsson planned the Millenium series as having ten installments, but due to his sudden death in 2004, only three were completed and published.

Question: what was the cause of death?
Self-contained rewrite: what was the cause of death for Stieg Larsson?