Thornton is a town in Grafton County, New Hampshire, United States.

Via the Pemigewasset, the town is part of the Merrimack River watershed.

The highest point in Thornton is 2,580 feet (790 m) above sea level on the western ridge of Dickey Mountain, whose 2,734-foot (833 m) summit lies in the neighboring town of Waterville Valley.

The White Mountain National Forest covers most of the eastern side of the town.

At the 2000 census there were 1,843 people, 759 households, and 507 families living in the town.