Charles III William (Durlach, – 12 May 1738, Karlsruhe) was Margrave of Baden-Durlach between 1709 and 1738. He was the son of Margrave Frederick Magnus of Baden-Durlach and Augusta Maria of Schleswig-Holstein-Gottorp. In 1715, he established Karlsruhe (Charles' repose), where he built his residence. Karlsruhe has since grown to a large city. With the consolidation of public finances and the creation of a reliable administration, he laid the foundations for the reform policies of his grandson, Charles Frederick.