Robert Phelan Langlands (1936-) is a Canadian mathematician who made fundamental contributions to the regresentation theory of locally compact semi-simple Lie groups.
In 1967 Langlands wrote a letter to André Weil which contains profound mathematical ideas which continue to drive a whole area of mathematical research. The letter was 17 pages hand-written and sent in January 1967. It sketched what soon became known as the Langlands conjectures here. The conjectures have far reaching consequences for the potential developement of non-abelian class field theory in number theory. He was appointed Herman Weyl Professor at the Institute for Advanced Study in 1972, becoming Professor Emeritus in January 2007. He won the [Wolf prize] in 1995/6.