Old Grand-Dad was a distiller named Basil Hayden who made his name by distilling a bourbon whiskey made with a higher percentage of rye for a lighter, spicier flavor. He passed along the art of distilling to his son 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.
— Distiller's notes