Mary Cain, American runner
Mary Cecilia Cain (born May 3, 1996) is an American professional middle distance runner from Bronxville, New York. Cain was the 2014 World Junior Champion in the 3000 meter event. She is the youngest American athlete ever to represent the United States at a track and field World Championships meet after competing in the 2013 World Championships in Athletics in Moscow aged 17 and 3 months.