John Oliver Johnstone (January 21, 1892 – February, 1969) was an American track and field athlete who competed in the 1912 Summer Olympics where he finished sixth in the high jump competition.
He spent much of his youth competing in track and field events throughout New England, attending the Edward Devotion School in Brookline and then going on to Worcester Academy before becoming the youngest member at the time to represent the USA in the Olympics in Stockholm, Sweden.
He graduated from Worcester Academy, where he attained status as World Schoolboy champion - winning American Athletic Association championships.
He graduated from Harvard in 1916 and moved with his wife, Ann Catherine Temple Jones, to Lewiston, Maine, where he was a professor of French and the Track Coach at Bates College.
The following year, John Oliver Johnstone III was born healthy and became known as "Jack".