Hannibal is an unincorporated community and census-designated place in eastern Ohio Township, Monroe County, Ohio, United States. It has a post office with the ZIP code 43931. In the 2020 Census, it had a population of 314, down from 411 in 2010.
Hannibal was originally called "Baresville", named for the founder Jacob Bare. A post office called Hannibal was opened and the town's name was soon changed to match. From Wikipedia
