James Adelbert Mulligan (June 30, 1830 – July 26, 1864) was colonel of the 23rd Illinois Volunteer Infantry Regiment in the Union Army during the American Civil War. On February 20, 1865, the United States Senate confirmed the posthumous appointment of Mulligan to the rank of brevet brigadier general of U.S. Volunteers to rank from July 23, 1864, the day before he was mortally wounded at the Second Battle of Kernstown, near Winchester, Virginia. He commanded the Federal forces at the First Battle of Lexington, and later distinguished himself in other engagements in the Eastern theater prior to his death in battle.