Hollis is a town in Hillsborough County, New Hampshire, United States. The population was 8,342 at the 2020 census, having grown 9% from the 2010 population of 7,684. The town center village is listed on the National Register of Historic Places as Hollis Village Historic District.

Hillsborough County is the most populous county in the U.S. state of New Hampshire. As of the 2020 census, the population was 422,937, almost one-third the population of the entire state. Its county seats are Manchester and Nashua, the state's two biggest cities. Hillsborough is northern New England's most populous county as well as its most densely populated.