Petter Johan Thomassen (17 April 1941 – 8 October 2003) was a Norwegian politician for the Conservative Party.
He was born in Salangen Municipality as a son of farmers Karl Thomassen (1905–1978) and Johanna, née Grimstad (1914–1996).
From 1985 to 1986, while Willoch's Second Cabinet held office, Thomassen served as the Minister of Industry.
[1] He chaired Nordland District College (1976 to 1978), Dataringen (1971 to 1973, board member 1968 to 1976), Nordlandsforskning (1980 to 1985, 1986 to 1988), Polarsirkelsenteret (1988 to 1990), Norsk Luftfartssenter (1994 to 1998), Polar Park (1994 to 2001), Bodø Energi (1996 to 2003), Nordland Teater (1999 to 2003) and Store Norske Spitsbergen Kulkompani (2003).
He was a board member of Norske datasentralers landsforbund (1972 to 1974) and the Norwegian Electricity Industry Association (1998 to 2003).