James Thacher (1754–1844) was an American physician and historical author born in Barnstable, Massachusetts. During the Revolutionary War, he served as a surgeon in the Massachusetts 16th Regiment and was a witness to the 1781 surrender of the British in Yorktown. In his Military Journal during the American Revolutionary War (1823), Thacher gives his account of the fighting and intrigue. He penned other historical volumes that chronicled American culture and politics in the post-Revolutionary War-era. Following the war, Thacher practiced medicine in Plymouth, Massachusetts. He married Susannah Hayward, and they had six children, although only two daughters survived into adulthood.