Old Grand-Dad was a real person, which should not surprise you if you've read any of the words on this page. He was a distiller named Basil Hayden who made his name by distilling a bourbon whiskey made with a higher percentage of rye. Basil Hayden passed along the art of distilling to his son Thyme (Just pulling your leg. We don't know his name) and then, in turn, to his grandson. It was the third generation distiller, Colonel R.B. Hayden, who honored his grandfather by naming his justly famed whiskey Old Grand-Dad.
During Prohibition, Old Grand-Dad was produced by a pharmaceutical company, the American Medicinal Sprits Co., and was one of the few distilled spirits permitted to be prescribed as medicine. It was a popular time to be sick.