Petrus Antonius "Peter" Lankhorst (born 1 January 1947) is a retired Dutch politician of the GreenLeft (GL) party.Lankhorst served as a Member of the House of Representatives from 10 June 1981 until 17 May 1994, first as a member of the Political Party of Radicals (PPR) and from 1990 as a member of GreenLeft. He became the Parliamentary leader of GreenLeft in the House of Representatives and the Leader of GreenLeft on 21 April 1993 after the resignation of Ria Beckers.