Warren is a town in Grafton County, New Hampshire, United States. The population was 825 at the 2020 census, down from 904 at the 2010 census. Warren includes the village of Glencliff. The Appalachian Trail crosses the town in the west.

Glencliff is an unincorporated community within the White Mountain National Forest in the town of Warren in Grafton County, New Hampshire, United States. The village consists of fewer than one hundred residents and some forty man-made structures, including the Willing Workers Hall, the Glencliff Community Chapel, the old firefighter's garage, the Glencliff Improvement Cooperative, the post office and the Glencliff Home for the Elderly.