Holmes County is a county located in the U.S. state of Ohio. As of the 2010 census, the population was 42,366. Its county seat is Millersburg. The county was formed in 1824 from portions of Coshocton, Tuscarawas and Wayne counties and organized the following year. It was named after Andrew Holmes, an officer killed in the War of 1812.A large Amish community of about 36,000 exists in Northeast-Central Ohio, centered on Holmes County and extending into surrounding counties.