Roundhead Township is one of the fifteen townships of Hardin County, Ohio, United States.

Located in the southwestern corner of the county, it borders the following townships: No municipalities are located in Roundhead Township, although the unincorporated community of Roundhead lies in the township's southeast.

[4] The township is named for Wyandot chief Roundhead, who inhabited the area in the early 19th century.

[5] The township is governed by a three-member board of trustees, who are elected in November of odd-numbered years to a four-year term beginning on the following January 1.

There is also an elected township fiscal officer,[6] who serves a four-year term beginning on April 1 of the year after the election, which is held in November of the year before the presidential election.