Lars Valter Hörmander (born January 24, 1931) is a Swedish mathematician. He received his PhD from Lund University in 1955. He spent some years working at various places including the Stockholm University, Stanford University, and the Institute of Advanced Study, before returning to Lund, where he stayed until retirement in 1996.

He was awarded the Fields medal in 1962, and the Wolf Prize in mathematics in 1988.

He is well known for his work in partial differential equations and to a lesser extent his work in several complex variables.