Wiles Robert Hunter was born on April 10, 1874, at Terre Haute, Indiana the middle of five children born over thirteen years to William Robert and Caroline "Callie" ("née" Fouts) Hunter. Hunter's father was a native of Tennessee and a veteran of the American Civil War, having served as a colonel with the Illinois 21st Infantry. At war's end William Hunter relocated to Terre Haute where he married and became a manufacturer of horse-drawn carriages and buggies in partnership with his father-in-law, Andrew B. Fouts. Robert Hunter's maternal second great-grandfather was Samuel Hawkins, an American Revolutionary War veteran who had served with General George Rogers Clark at the Battle of Vincennes.