Ner Middleswarth (December 12, 1783 – June 2, 1865) was an American politician from New Jersey who served as a Whig member of the U.S. House of Representatives for Pennsylvania's 10th congressional district from 1853 to 1855.
John Middleswarth served as a Quartermaster Sergeant for Colonel Sylvanus Seely's regiment in the New Jersey militia during the American Revolution.
John Middleswarth was from the Van Middleswaert family, who came from the Netherlands to New Amsterdam to Flatbush and then moved to Somerset, New Jersey in the 1690s.
In 1812, Ner Middleswarth raised a company of Volunteers and entered the war of 1812 as captain, attached to the Pennsylvania Riflemen.
Again in 1814, he raised another company which was attached to General Thomas McCall Cadwalader's Division, commanded by Colonel Uhl during the Niagara campaign.
He lost a great deal of his wealth, however, on a failed iron business called "Beaver Furnace" near Paxtonville, Pennsylvania.