Walter W. Horn (18 January 1908 – 26 December 1995) was a medievalist scholar noted for his work on the timber vernacular architecture of the Middle Ages. He was born in Germany, but fled Nazism and spent most of his academic career at the University of California, Berkeley, where he became the university system's first art historian and co-founded the History of Art department. A naturalized citizen of the United States, Horn served in the U.S. Army during World War II and then in the special intelligence unit that tracked down art works plundered by the Nazis. His most celebrated exploit was the recovery of the crown jewels of the Holy Roman Empire, also known as Charlemagne's Imperial Regalia. As a scholar, Horn is most noted for his work on the medieval architectural drawing known as the Plan of Saint Gall.