John Horton Slaughter (October 2, 1841 – February 16, 1922), or sometimes Texas John Slaughter, was an American lawman, Civil War soldier, and gambler. Over the course of his long life, John Slaughter served as an honorable soldier and lawmen throughout much of the Southwest. He fought in many skirmishes against all sorts of enemies, including Union soldiers, hostile natives, and Mexican and American outlaws. In the latter half of his life, he lived at the San Bernardino Ranch, which is now a well-preserved historic site in southern Arizona.