Klimt, Gustav (1862-1918), Viennese painter, who was the founder of the Vienna Secession, the Austrian art nouveau movement. His early work, consisting principally of large murals for theaters, was painted in an unremarkable naturalistic style. After 1898, Klimt's work moved toward greater innovation and imagination, taking on a more decorative, symbolic aspect. He continued to paint murals, but the harsh public criticism of the three murals Philosophy, Medicine, and Jurisprudence (1900-1902, Vienna University; destroyed 1945) led him to concentrate on panel painting. Klimt's best-known works are his later portraits, such as Frau Fritsa Reidler (1906, Österreichische Galerie, Vienna), with their flat, unshadowed surfaces, translucent, mosaic colors and forms, and sinuous, curling background lines and patterns. Among his most admired works is the series of mosaic murals (1905-1909) in the Palais Stoclet, an opulent private mansion in Brussels designed by the architect Josef Hoffmann, who was also a member of the Vienna Secession movement.