| Henry St. John | |
| State: | Ohio |
| Term Start: | March 4, 1843 |
| Term End: | March 3, 1847 |
| Preceded: | Calvary Morris |
| Succeeded: | Rodolphus Dickinson |
| Party: | Democratic |
| Birth Date: | 16 July 1783 |
| Birth Place: | Washington County, Vermont |
| Death Place: | Tiffin, Ohio |
| Allegiance: | United States |
| Branch: | United States Army |
| Battles: | War of 1812 |
Henry St. John (July 16, 1783May 17, 1869) was a U.S. Representative from Ohio.
Born in Washington County, Vermont, St. John received limited schooling.He served during the War of 1812 before moving to Wooster, Ohio, in 1815. Later, he moved to Crawford County, Ohio. In 1837, he settled in Seneca County, where he engaged in agricultural pursuits, milling, and storekeeping near Tiffin, Ohio.
St. John was elected as a Democrat to the Twenty-eighth and Twenty-ninth Congresses (March 4, 1843 – March 3, 1847).He was not a candidate for renomination.After leaving Congress, he resumed agricultural pursuits.Resided in Tiffin, Ohio, where he died in May 1869.