John Nihill (May 25, 1850 – May 29, 1908) was an Irish-born soldier in the U.S. Army who served with the 5th U.S. Cavalry during the Indian Wars. A participant in the Apache Wars, he received the Medal of Honor for bravery when he single-handedly fought off four Apache warriors in the Whetstone Mountains of Arizona on July 13, 1872. At the time of his death, he was the only enlisted man to be admitted as a member of the Military Order of the Loyal Legion of the United States.