| Election Name: | 1855 Ohio gubernatorial election |
| Country: | Ohio |
| Type: | presidential |
| Ongoing: | no |
| Previous Election: | 1853 Ohio gubernatorial election |
| Previous Year: | 1853 |
| Next Election: | 1857 Ohio gubernatorial election |
| Next Year: | 1857 |
| Election Date: | October 9, 1855 |
| Nominee1: | Salmon Chase |
| Party1: | Republican Party (United States) |
| Popular Vote1: | 146,770 |
| Percentage1: | 48.59% |
| Nominee2: | William Medill |
| Party2: | Democratic Party (United States) |
| Popular Vote2: | 131,019 |
| Percentage2: | 43.37% |
| Nominee3: | Allen Trimble |
| Party3: | Know Nothing |
| Popular Vote3: | 24,276 |
| Percentage3: | 8.04% |
| Governor | |
| Before Election: | William Medill |
| Before Party: | Democratic Party (United States) |
| After Election: | Salmon Chase |
| After Party: | Republican Party (United States) |
The 1855 Ohio gubernatorial election was held on October 9, 1855. Incumbent Democratic Governor of Ohio William Medill became governor after the resignation of Reuben Wood to accept a consulship, and Lt. Governor Medill became elected in his own right in 1853. The 1855 election was one of the first major tests of the fledgling Republican Party, then still a coalition of various anti-slavery forces, including former rival Democrats and Whig members. This election led them to quickly dominate Ohio politics for the next half-century.
The election is also unique in that it was a contest of three Governors, past, present, and future. With Allen Trimble having served in the 1820s, William Medill serving at the time of the election, and Salmon Chase succeeding Medill. Trimble proved to be somewhat of a spoiler candidate, leaving Chase to win with only a plurality of the votes.