James Compton, 3rd Earl of Northampton FRS (19 August 1622 – 15 December 1681), was an English peer, politician and author, who fought for the Royalists during the First English Civil War. He succeeded his father Spencer Compton, 2nd Earl of Northampton when he was killed in March 1643 at the Battle of Hopton Heath. After the war ended in Royalist defeat in 1646, he spent the next 14 years living quietly on his estates, although he was arrested several times on suspicion of involvement in conspiracies to restore Charles II.