Though it started small and with no original programming of its own, HBO grew to the point in which it dominated the last two decades of cable television. But to remain atop the Iron Throne, the company will need to change and grow. This isn't the War of Five Kings, but of dozens of would-be usurpers – many of whom are backed by untold billions and orthogonal business models. Here, REDEF covers where HBO is today and how it got there, who it now competes against, and the moves it needs to make.