The enemy isn’t a single species, or even a distinct political faction. Though it has a leader - or at least a “head”, or a “founder” - to focus on the leader would be pointless. The enemy is a process. To understand the enemy it’s necessary to understand how that process works, and a simple one-word name would only encourage the Houses to concentrate on the much less important details of, say, the enemy’s physical appearance (they can barely grasp their opponents’ operating principles at the best of times). To put it simply: the important thing isn’t who the enemy is, but whyit is.
obsessed obsessed obsessed with “the enemy is a process” in perfect contrast to the houses being functions - the enemy is a threat in part or perhaps even primarily because inherent to the enemy is change, the one thing that threatens the time lords and the one things they can never do
So in Torchwood: Miracle Day, we see that a group called “the Family”, including members called “the Cousin” and “the Mother”, cause all of humanity to become immortal by pouring Jack’s biodata into a mysterious crack running through the center of the Earth. I’m not saying it’s Faction Paradox messing around with Earth’s caldera - how could I? We see that the Family are just regular old humans! Though, come to think of it, Big Finish’s Torchwood audios do say that the Family was being controlled by a mysterious groups of aliens …
In fact, per The Torchwood Archive, the mysterious alien Committee controlling the Families later created a force capable of possession – a force which defeated its creators and waged a war against humanity, who forgot its name and called it only “The Enemy”.
