Duncan McArthur (1772 – April 29, 1839) was a military officer and a Federalist and National Republican politician from Ohio. He served as the 11th governor of Ohio. When first elected to state office as a representative, he was serving in the state militia during the War of 1812. He was later appointed as brigadier general in the U.S. Army. Shortly thereafter he was placed in charge of the Army of the Northwest, serving through 1817 and negotiating the Treaty of Fort Meigs of 1817 to ratify peace and land cessions with Native American tribes.