Thomassen (born 23 September 1945) is a Dutch organizational theorist, Emeritus Professor of Political Science at the University of Twente, and member of the Royal Netherlands Academy of Arts and Sciences, known for his work on the theory of political and policy representation.
[4] In 1968 he started his academic career as assistant professor at the Tilburg University.
After his graduation in 1977 he was appointed Professor of Political science at the University of Twente, where he served the rest of academic career.
[4] In the years 1986–87 and 2002–03 he was fellow at the Netherlands Institute for Advanced Studies in the Social Sciences (NIAS).
Since 1991 he is member of the Royal Netherlands Academy of Arts and Sciences.