William Plumer

William Plumer (June 25, 1759 – December 22, 1850) was an American lawyer and Baptist lay preacher from Epping, New Hampshire. Born in 1759 in Newburyport, Massachusetts, he represented New Hampshire as a Federalist in the United States Senate from June 17, 1802 to March 4, 1807. Plumer later became a Democratic-Republican and serve as a Governor of New Hampshire, 1812–1813 and 1816–1819.

In the 1820 presidential election, he cast the only dissenting vote in the Electoral College against incumbent President James Monroe, voting instead for John Quincy Adams. While some accounts say that this was to ensure that George Washington remained the only American president unanimously chosen by the Electoral College, others assert that he was instead calling attention to his friend Adams as a potential future presidential candidate, or protesting against the "wasteful extravagance" of the Monroe Administration. Plumer also eschewed voting for Daniel D. Tompkins for Vice President as "grossly intemperate" and having "not that weight of character which his office requires," and also "because he grossly neglected his duty" in his "only" official role as president of the Senate by being "absent nearly three-fourths of the time." Plumer instead voted for Richard Rush.

In 1803, Plumer was one of several New England Federalists who proposed secession from the United States due to lack of support for Federalists, rising influence of Jeffersonian Democrats and the diminished influence of the North due to the Louisiana Purchase.

Plumer was a founder and the first president of the New Hampshire Historical Society. He died in 1850, aged 91, at Epping, New Hampshire.

William Plumer was the father of William Plumer, Jr., who served in the United States House of Representatives.