The Great Hanging at Gainesville was the execution by hanging of 41 suspected Unionists in Gainesville, Texas, in October 1862 during the American Civil War. Confederate troops shot two additional suspects trying to escape. Confederate troops captured and arrested some 150–200 men in and near Cooke County at a time when numerous North Texas citizens opposed the new law on conscription. Many suspects were tried by a "Citizens' Court" organized by a Confederate military officer. It made up its own rules for conviction and had no status under state law. Although only 11% of county households enslaved people, seven of the 12 men on the jury were enslavers.

Gainesville is a city in and the county seat of Cooke County, Texas, United States. Its population was 17,394 at the 2020 census. It is part of the Texoma region and is an important Agri-business center.