Karl Anselm, 4th Prince of Thurn and Taxis /German: Karl Anselm Fürst von Thurn und Taxis; 2 June 1733 – 13 November 1805/ was the fourth Prince of Thurn and Taxis, Postmaster General of the Imperial Reichspost, and Head of the Princely House of Thurn and Taxis from 17 March 1773 until his death on 13 November 1805. Karl Anselm served as Prinzipalkommissar at the Perpetual Imperial Diet in Regensburg for Joseph II, Holy Roman Emperor and Francis II, Holy Roman Emperor from 1773 to 1797. He was awarded with the Golden Fleece Order in 1750.