John Gwinn III (June 11, 1791 – September 1, 1849) was a United States Navy officer born in Maryland. During the War of 1812, he was a POW after the Royal Navy had captured Frolic in 1814 and he later commanded Vandalia.
As Captain of USS Constitution, Gwinn sailed on December 9, 1848 and arrived at Tripoli on January 19, 1849. While transporting Daniel Smith McCauley and his family to Egypt, McCauley's wife gave birth to a son, who was named Constitution Stewart McCauley. At Gaeta on August 1 Gwinn received on board King Ferdinand II and Pope Pius IX. This would be the first time a Pope had set foot on American territory. At Palermo on September 1, 1849, Captain Gwinn died of chronic gastritis and was buried near Lazaretto on the 9th, ending a forty-year Navy career. Gwinn's body was moved to Glenwood Cemetery in Philadelphia, Pennsylvania a few years later and remained there until 1931 when his body was moved to Arlington National Cemetery.