Sir William Dennis Pile GCB MBE (1 December 1919 – 26 January 1997) was an English civil servant.
Educated at St Catharine's College, Cambridge, he served in the Army during the Second World War, reaching the rank of Major.
After completing his degree, he entered the Ministry of Education in 1947, serving on the UK delegation to UNESCO and then spending a year at the Cabinet Office (1950–51) before returning to the Ministry, which became the Department for Education and Science (DES) in 1964.
From 1966 to 1970, he spent short periods at the Ministry of Health and the Home Office, the later as deputy secretary from 1967.
In retirement, he was a director of Nationwide Building Society and The Distillers Company.