Martin Luther Smith (September 9, 1819 – July 29, 1866) was an American soldier and civil engineer, serving as a major general in the Confederate States Army. Smith was one of the few Northern-born generals to fight for the Confederacy, as he had served most of his early military career in the South with the United States Army's topographical engineers, marrying a native of Athens, Georgia. He planned and constructed the defenses of Vicksburg.