Guillaume Jacques (Chinese: 向柏霖; pinyin: Xiàng Bólín) is a French linguist of Breton descent who specializes in the study of Old Chinese, Tangut, Tibetan, Rgyalrongic and Kiranti languages. He has also done research on the Breton language. His case studies in historical phonology are set in the framework of panchronic phonology, aiming to formulate generalizations about sound change that are independent of any particular language or language group.He was awarded the CNRS Bronze Medal in 2015.