William Melvin was born on 20 November 1920 in Kingston, Ontario, the son of Dr George Spencer Melvin, a physiologist and dean of medicine at Queen's University in Kingston, and Isabella, née Stewart, a nurse. He was educated at Upper Canada College and Queen's University Medical School in Kingston, and graduated in 1943. In the latter days of the war he served as a surgeon-lieutenant in the Royal Canadian Naval Volunteer Reserve, and in 1945 he married Kathleen, née Marling, a nurse. From 1952 to 1965 he was associate professor of surgery at Kingston General Hospital and the Hôtel Dieu Hospital, and he also worked at Scarborough General Hospital in Ontario. He was a keen sportsman, interested in football and hockey, and he was the founding President of the Canadian Academy of Sports Medicine. He and his wife had two children - a son, Alex, and a daughter, Susan, both of whom took university degrees. He died on 31 December 1991, aged 71.