William of Sens or Guillaume de Sens was a 12th-century French master mason and architect, believed to have been born at Sens, France. He is known for rebuilding the choir of Canterbury Cathedral between 1174 and 1177, counted as the first important example of the Early Gothic Style of architecture in England, finished in 1184. Before Canterbury, he worked on Sens Cathedral. According to one English source, he died at Canterbury on 11 August 1180. According to other sources, he died in France, after returning from England.