Orrin Lorentna Mann (November 25, 1833 – December 13, 1908) was an American soldier and politician who served as an officer in the Union Army during the American Civil War. Born in Ohio, Mann struggled to find gainful employment in his early years and made two abortive attempts to gain a university education. While in Chicago, Illinois, Mann raised a regiment, the 39th Illinois Volunteer Infantry Regiment, which deployed in late 1861. Mann led the unit through the First Battle of Kernstown and Siege of Fort Wagner before sustaining an injury while leading at the Battle of Drewry's Bluff. During this latter engagement, Mann was promoted to brigadier general. He spent most of the rest of the war as the Provost Marshal of Norfolk, Virginia.