Jan Cornelis Terlouw (born November 15, 1931) is a Dutch scientist, politician, and author.
Jan Terlouw was born in Kamperveen. After high school, Terlouw studied mathematics and physics at Utrecht University. After graduating, he worked as a physics researcher in the Netherlands, the United States, and Sweden. After working for thirteen years, he became a politician, joining the Dutch Tweede Kamer (the second chamber of the Dutch legislature) as a member of the Democraten 66 political party in 1967. Terlouw acted as party leader from 1973-1982. He also wrote various children's books, notably Winter in Wartime (1976) and How to Become King (1978). Terlouw is currently married and has four children.