| William David Knowles | |
| Birth Date: | 16 February 1908 |
| Birth Place: | Langton, Ontario, Canada |
| Parliament: | Canadian |
| Riding: | Norfolk—Haldimand |
| Term Start: | 25 June 1968 |
| Term End: | 21 March 1979 |
| Predecessor: | Jack Roxburgh |
| Successor: | District abolished |
| Profession: | Teacher |
| Party: | Progressive Conservative |
William David Knowles (16 February 1908 – 23 November 2000) was a Progressive Conservative party member of the House of Commons of Canada. He was born in Langton, Ontario and became a teacher by career.
He was first elected at the Norfolk—Haldimand riding in the 1968 general election, defeating Jack Roxburgh. He was re-elected there in the 1972 and 1974 federal elections and completed his term in the 30th Parliament before leaving federal political office.