William "Bull" Nelson, American general (b. 1824)
William "Bull" Nelson (September 27, 1824 – September 29, 1862) was a United States naval officer who became a Union general during the American Civil War.

As a Kentuckian, Nelson could have sympathized with the Confederates but threw in his lot with the Union. Secretary of Treasury Salmon P. Chase believed Nelson's actions had kept Kentucky loyal and promoted him to brigadier general in September 1861. Nelson's 4th Division bore the brunt of heavy fighting at the Battle of Shiloh and took part in the Siege of Corinth; he was the first man to enter the town.

Wounded at the Battle of Richmond, Nelson was forced to retreat to Louisville to plan a new assault. It was there that General Jefferson C. Davis, still officially on sick leave, reported to Nelson, who was dissatisfied with his performance and insulted him in front of witnesses. A few days later, Davis demanded a public apology, however, the situation rapidly escalated into a physical confrontation, which concluded in Davis mortally wounding Nelson with a pistol.