Kjell Ola Dahl, born 1958, is an award-winning novelist specialized in crime fiction. He also writes screenplays and non-fiction. His debut novel was Lethal Investments, the first book in the Oslo Detectives series. His latest novel, The Assistant, was published in Norway in 2020 and England, Canada and the US in 2021. Dahl and Hisham Zaman have co-written the scripts for the feature films Winterland and Before Snowfall. Dahl is a member of the board of Snowfall Cinema.