Mrs. Dorothy Killam, née Dorothy Brooks Johnston, was born in St. Louis in 1899, of moderately affluent parents. She was well-schooled, with a good knowledge of French and German, athletic and widely travelled. Unlike her reticent husband, Dorothy Killam was an extrovert who loved company and people generally. After she and Mr. Killam were married in 1922, they lived in Montreal, the centre of the Killam financial empire.

Izaak Walton Killam died suddenly and unexpectedly of heart failure in 1955 at his Québec fishing lodge. He left all of his substantial estate to his wife, who subsequently demonstrated her own financial acumen by vastly increasing the fortune over the next 10 years. When Mrs. Killam died in 1965, after several years of poor health, she left a Will which gave effect to the plans she and her husband had discussed frequently in the later years of his life. While Mrs. Killam's Will for the most part reflected the intentions of her husband, it also included a substantial bequest to build a children's hospital in Halifax as a memorial to Mr. Killam.