William Mervin Mills, also known by his Oglala Lakota name Tamakhóčhe Theȟíla, is an American Oglala Lakota former track and field athlete who won a gold medal in the 10,000 metre run (6.2 mi) at the 1964 Tokyo Olympics. His 1964 victory is considered one of the greatest Olympic upsets because he was a virtual unknown going into the event. He was the first non-European to win the Olympic event and remains the only winner from the Americas. He was also a United States Marine officer.