John Cleves Symmes (1779 - May 1829) was born in New Jersey to Timothy Symmes. In some local dealings he used the name Junior to distinguish himself from his prominent uncle John Cleves Symmes. He died in May of 1829 and is buried in Symmes Park at Hamilton, Ohio.

He joined the United States Army in 1802 and rose to the rank of Captain during the War of 1812. In that war he served on the Canadian frontier, at both Fort Niagara and Fort Eire.

His 1818 theory of a Hollow Earth, envisaging a shell about 800 miles thick, with openings at both poles about 1400 miles across, made his name famous/notorious. He proposed the name Symzonia for the inner territories.

See a current reprint of his book: Symzonia; Voyage of Discovery, ISBN 0405063121.

Compare a fictional echo of Symmes in Ian Wedde's Symmes Hole (1987).