Chief executive officer - chief operating officer (CEO-COO) duos have been around for a few decades. Also known as chief executive-managing director duos, until recently COOs have not received much attention from management academics, the business-financial press or others outside the company. The spotlight remained firmly on the external-facing chief executive. There is now growing interest in this crucial yet largely externally-low-profile role which has been called the toughest job in the company.