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 Southwest. After serving in the Confederate States Army during the American Civil War of 1861-1865, he fought against hostile Indians, Mexican and American outlaws. In the latter half of his life, he lived at the San Bernardino Ranch, a well-preserved National Historic Landmark in Cochise County in far southeastern Arizona.