Gerardus Heymans (Dutch: ; 17 April 1857 – 18 February 1930) was a Dutch philosopher and psychologist. From 1890 to 1927, he worked as a professor of philosophy at the University of Groningen (UG). He also served as rector magnificus (president) of the UG in the academic year 1908–1909. Heymans is one of the most influential philosophers of the Netherlands and the pioneer of Dutch psychology. The establishment of his psychological laboratory marked the start of experimental psychology in the Netherlands.