Dummer is a town in Coös County, New Hampshire, United States. The population was 306 at the 2020 census. It is part of the Berlin, NH–VT micropolitan statistical area. Dummer is home to the Pontook Reservoir, popular with canoeists, kayakers and birdwatchers. In the western part of Dummer lies the village of Paris.

Coös County or Coos County is a county in the U.S. state of New Hampshire. As of the 2020 census, the population was 31,268, making it the least-populated county in the state. The county seat is Lancaster.