Herman Diederik Tjeenk Willink (Amsterdam, 23 January 1942) is a Dutch former politician for the Labour Party and former senior civil servant. From 1991 to 1997 he was President of the Senate of the States General. From 1997 to 2012 he was Vice President of the Council of State. Since December 2012, Tjeenk Willink has been Minister of State. He acted as informateur during five different cabinet formations and cabinet crises.