Hunter was born in New Orleans, Louisiana, the son of Edith Lois (Burgess) and Henry Herman McKinnies. His family was of Irish Catholic ancestry. After 1930, he was reared in Milwaukee, Wisconsin, where he graduated from Whitefish Bay High School. He was very involved in school sports and began acting in local theater and radio in his early teens. He worked for station WTMS-FM and the Children's Theatre of the Air, sponsored by the Wauwatosa School Board.