| John S.C. Knowlton | |
| Office: | 15th Sheriff of Worcester County, Massachusetts |
| Term Start: | 1857 |
| Term End: | 1871 |
| Successor: | Augustus B. R. Sprague |
| Term Start2: | January 3, 1853 |
| Term End2: | January 1, 1855 |
| Predecessor2: | Peter C. Bacon |
| Successor2: | George W. Richardson |
| Term Start3: | 1852 |
| Term End3: | 1853 |
| Birth Name: | John Stocker Coffin Knowlton |
| Birth Date: | 11 December 1798 |
| Death Place: | Worcester, Massachusetts |
| Nationality: | American |
| Spouse: | Anna W. Hartwell |
John Stocker Coffin Knowlton (December 11, 1798 – June 11, 1871) was an American newspaper editor, publisher and politician who served in both branches of the Massachusetts legislature, as the Mayor of Worcester, Massachusetts, and as the Sheriff of Worcester County, Massachusetts.
Knowlton was born in Hopkinton, New Hampshire to Daniel Knowlton and Mary Stocker. Knowlton attended Hopkinton and Phillips Andover academies, and graduated from Dartmouth College in 1823.
Knowlton married Anna W. Hartwell, of Littleton, Massachusetts on September 17, 1829. He died in Worcester on June 11, 1871.