Hamler is a village in Henry County, Ohio, United States. The population was 600 at the 2020 census. Hamler is a rural farming community in Northwest Ohio about 40 miles (64 km) southwest of Toledo, Ohio. It is located at the intersection of the former Baltimore and Ohio (B&O) and former Detroit, Toledo and Ironton railroads and the intersection of Ohio State Route 109 and Ohio State Route 18.

Henry County is a county located in the U.S. state of Ohio. As of the 2020 census, the population was 27,662. Its county seat is Napoleon. The county was created in 1820 and later organized in 1834. It is named for American Founding Father Patrick Henry, the Virginian famous for his "give me liberty, or give me death!" speech.