| William Thomas Lockhart | |
| Office1: | Ontario MPP |
| Term Start1: | 1890 |
| Term End1: | 1894 |
| Predecessor1: | James Wellington McLaughlin |
| Successor1: | William Henry Reid |
| Constituency1: | Durham West |
| Party: | Liberal |
| Birth Date: | 29 November 1838 |
| Death Place: | Bowmanville, Ontario |
| Occupation: | Merchant |
William Thomas Lockhart (November 29, 1839 - June 4, 1900) was an Ontario merchant and political figure. He represented Durham West in the Legislative Assembly of Ontario as a Liberal member from 1890 to 1894.
He was born in Smith Township, Peterborough County, Upper Canada in 1839 and educated in Oshawa. In 1880, he married Mary Renwick. Lockhart was a grain dealer in Newcastle. He served in the local militia. Lockhart was defeated in his bid for reelection in 1894. He died at Bowmanville in 1900 after a brief illness.[1]