Sir William John Pugh OBE FRS (28 June 1892 – 18 March 1974) was a British geologist who was director of the Geological Survey of Great Britain and of the Museum of Practical Geology, Department of Scientific and Industrial Research. During World War I, he served with the Royal Welch Fusiliers as a staff officer, rising to the rank of major. He was awarded OBE in the 1919 New Year Honours, the French Croix de Guerre and was twice mentioned in despatches.