Cornelis Constant Maria (Kees) Vendrik (Nijmegen, 30 january 1963) is a Dutch politician. He is member of the Tweede Kamer for the GreenLeft. Vendrik studied political science at the Radboud University Nijmegen and the University of Amsterdam. After his studies he worked for the debating centre De Balie in Amsterdam and as assistant of the GreenLeft parliamentary party in the Tweede Kamer. Vendrik is the party's specialist on the economy, finance, the health care system and international trade. He is an advocate of the use of open source software by government agencies.