Duncan McArthur (June 14, 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 and commanded a brigade under General William H. Harrison during the battle of the Thames.