Egbert Rudolf van Kampen (28 May 1908, Berchem, Belgium – 11 February 1942, Baltimore, Maryland) was a mathematician. He made important contributions to topology, especially to the study of fundamental groups.
Van Kampen received his Ph.D. degree from Leiden University in 1929. His dissertation, entitled Die kombinatorische Topologie und die Dualitaetssaetze, was written under the direction of Willem van der Woude.
In 1931 van Kampen left Europe and travelled to the United States to take up the position which he had been offered at Johns Hopkins University in Baltimore, Maryland. There he met Oscar Zariski who had taught at Johns Hopkins University as a Johnston Scholar from 1927 until 1929 when he had joined the Faculty. Zariski had been working on the fundamental group of the complement of an algebraic curve, and he had found generators and relations for the fundamental group but was unable to show that he had found sufficient relations to give a presentation for the group. Van Kampen solved the problem, showing that Zariski's relations were sufficient, and the result is now known as the Zariski–van Kampen theorem. This led van Kampen to formulate and prove what is nowadays known as the Seifert–van Kampen theorem.