William Plumer was an American lawyer, Baptist lay preacher, and politician from Epping, New Hampshire. He is most notable for his service as a Federalist in the United States Senate (1802–1807), and the seventh governor of New Hampshire as a Democratic-Republican.

Epping is a town in Rockingham County, New Hampshire, United States. The population was 7,125 at the 2020 census, up from 6,411 at the 2010 census.