John Horton Slaughter (October 2, 1841 – February 16, 1922), also known as Texas John Slaughter, was an American lawman, cowboy, poker player and rancher in the Southwestern United States during the late 19th and early 20th centuries. After serving in the Confederate States Army during the American Civil War, Slaughter earned a reputation fighting hostile Indians and Mexican and American outlaws in the Arizona and New Mexico territories. In the latter half of his life, he lived at the San Bernardino Ranch, which is today a well-preserved National Historic Landmark in Cochise County in far southeastern Arizona. In 1964, he was inducted into the Hall of Great Westerners of the National Cowboy & Western Heritage Museum.