Nathaniel Gray Smith Hart (c. 1784 – January 23, 1813), often Nathaniel G. S. Hart, was a well-connected Lexington, Kentucky lawyer and businessman, who served with the state's volunteer militia during the War of 1812. As Captain of the Lexington Light Infantry from Kentucky, Hart was killed with many of his men in the River Raisin Massacre of January 23, 1813, after being taken prisoner the day before following the Battle of Frenchtown in Michigan Territory.