John Claudius Kirk was a human pilot, a lieutenant in the United States Army Air Corps during World War II. His serial number was 0-159466. He was an ancestor of James T. Kirk. Kirk's middle name was due to his grandfather's interest in Latin studies, but Kirk was embarrassed by it while in school and hid it from his classmates. Kirk had one sister, who by 1942 worked for the U.S.O. and was engaged to a man named Capelli; their father was dead by that year. Like his famous descendant, Kirk enjoyed a good time. He became acquainted with a Russian soldier named Ivan Romanoff during a "wild night in Moscow".