Plain Township is one of the nineteen townships of Wood County, Ohio, United States. The 2020 census found 1,625 people in the township.

Wood County is a county located in the U.S. state of Ohio. As of the 2020 census, the population was 132,248. Its county seat is Bowling Green. The county was named for Captain Eleazer D. Wood, the engineer for General William Henry Harrison's army, who built Fort Meigs in the War of 1812. Wood County is part of the Toledo, OH Metropolitan Statistical Area. Its diagonal northwest border is formed by the Maumee River, which has its mouth at Maumee Bay on Lake Erie.