The Nihilanth

The Nihilanth is one of the largest, if not THE largest creature belonging to the realm of the Earth-Xen Borderworld. To date, it is the only one known of its kind and a creature of high intellect. While most creatures of Xen seem primitive in nature, lacking the ability to speak or communication, the Nihilanth is the one notable exception, one who is reportedly responsible for holding opening the Portals during the initial Black Mesa Incident and allowing his forces to pour through.

Public knowledge regarding the Nihilanth is limited, most only learning through the stories of Gordon Freeman told second-hand or that of the tales of the Vortigaunt tribes that Humanity has interacted with. 

But what is known is the creature is one of immense power, presumably wielding the Vortessence or its own form of "magic" that allowed it to perform feats seen as impossible by modern sciences. It could perform powerful psychic feats, allowing it to dominate and control the minds of its subjects leading it to run away from the Combine due to the Combines interest in wiping the Nihilanth kind out as a potential threat. The Nihilanth found the Borderworld and knew escape, and preparation were its only chance.

The first thing the Nihilanth did was fragment itself as a failsafe; Kingpins were created to rule as seconds in command, and its successor in the event of its death. The Controllers were also created, aerial units that used energy based attacks to control or kill their foes, an extension of the Nihilanths psychic powers.

Once the stage was set, the Nihilanth began to adopt, or kidnap, species from all quarters of space, incorporating them into one singular grand war machine in the loose hope to fight back, resistance on a grand scale. 

Xen, the borderworld became its home, its fortress, its last hope. 

Denizens of Xen began to be collected, brought and called upon, indoctrinated or enslaved to its designs. Efficiency was upheld through oppression; the Nihilanth knew to fight the unstoppable Empire, it had to, in itself, become the very thing it was fighting against. The Xenian dominion was created, settled, and prepared. Dozens of species joined in its glory, working in harmony; everything had a part to play in its plans, from the Kingpins all the way down to the lowly headcrab. An ecosystem was created, a world where no world existed, one could almost describe it as a utopia, if it weren’t for the ceaseless preparations for war. Machines of grand power, selective breeding, mystic defences, even the very flora of Xen were designed to kill. 

There was then there was a intrusion. Not by the Combine, but by a primitive race that had violated the sanctity of their home, who had no right to possess the technology to enter his domain. It was the Nihilanth’s right to punish them.

Then, the Freeman entered Xen and, guided by a mysterious hand, killed the Nihilanth, throwing the utopia into absolute chaos; everything he had worked for was torn apart in just a few moments. Whether for good or for worse.