| John Henry Douglas | |
| Office1: | Ontario MPP |
| Term Start1: | 1898 |
| Term End1: | 1902 |
| Predecessor1: | William Arnson Willoughby |
| Successor1: | William Arnson Willoughby |
| Constituency1: | Northumberland East |
| Party: | Liberal |
| Birth Date: | 22 June 1851 |
| Birth Place: | Warkworth, Canada West |
| Death Place: | Toronto, Ontario |
| Occupation: | Farmer |
John Henry Douglas (June 22, 1851 - December 12, 1930) was a farmer and politician in Ontario, Canada. He represented Northumberland East in the Legislative Assembly of Ontario from 1898 to 1902 as a Liberal.
The son of Donald Douglas and Elizabeth Waters, he was born in Warkworth, Canada West. In 1880, he married Clara Jane Boyce. His election in 1898 was declared void but he was reelected in a by-election held in December later that same year.[1]