Alf Reidar Jacobsen (born 21 February 1950) is a Norwegian journalist, non-fiction writer, novelist, crime fiction writer and biographer.

Jacobsen was born in Hammerfest. He has worked as a journalist for the newspapers Finnmark Dagblad, Klassekampen, Verdens Gang, for the magazine Økonomisk Rapport, and for the Norwegian Broadcasting Corporation.^[1]

He was awarded the Riverton Prize in 1988 for the novel Kharg.^[1] His book Iskyss from 1991, on Soviet espionage in Norway, earned him the SKUP Award,^[2] and was the basis for a film in 2008.^[1] He published a biography of the whaler Svend Foyn in 2008.^[1]

His book Kongens nei was the basis for the 2016 film The King's Choice. The film won eight Amanda Awards.^[1]

• Stalin's Gold – crime novel, Bladkompaniet (1982)
• The Adventure of Anders Jahre – non-fiction, Oktober (1982)
• The Bergersen Dynasty – non-fiction, Atheneum (1984)
• The Stock Market Sharks – non-fiction co-authored with Geir Imset, Pax (1985)
• The Moles: Norwegian Intelligence from World War I to Arne Treholt – non-fiction, Pax (1985)
• The Battle for Cosmos – non-fiction, Pax (1986)
• Osiris – crime novel, Pax (1986)
• Kværner, War: Diary of a Share Raid – non-fiction, Cappelen (1987)
• The Nonviolence Case – drama (1987)
• Kharg – crime novel, Tiden (1988)
• The Black Chamber: The Innermost Secret – non-fiction co-authored with Egil Mørk, Cappelen (1989)
• Ice Kiss – non-fiction, Aschehoug (1991)
• Running Risk – non-fiction co-authored with Jan Erik Langangen, Aschehoug (1992)
• They Knew Everything: A Documentation of the Ninth Floor – non-fiction co-authored with Ronald Bye and Finn Sjue, Tiden (1993)
• Without Scruples – non-fiction, Økonomisk rapport (1993)