The Kingpins
The Kingpins - Xen's remaining commanders
During the rule of the Nihilanth, a group of creatures dubbed kingpins were created to act as lieutenants for the rule that the Nihilanth established. Not much is known about them beyond the fact only a few remain- mostly the ones on Earth as the status of their Xenian brothers currently sits as a massive unknown, but can be presumed the Combine wiped them out after taking Xen under their control.
They were creatures of fragmented amalgamations of flesh, designed to be the Nihilanth's successors. But once their ruler had died, the Kingpins were trapped in a power vacuum, failing their original purpose of co-opting the dominion as they sought complete power. They numbered roughly around twelve originally; however, many fell in the initial invasion of Xen by the Combine Empire.
Each Kingpin possessed powerful abilities but each was unique based on their individual ruling style, purpose and overall power they had. While none of them are as strong as a Nihilanth, they are at least considered powerful beings who can manipulate their local space to their desire.
A few abilities are at least common among a few of them, such as the act of teleportation, taking an astral form to project their presence elsewhere; akin to how Vorts use the Vortessence to sometimes allow them to project themselves to another location without physically being in harms way. And of course they could each manifest their own unique and personalized artifact designed to help them control and use their power more efficiently at the cost of a heavy fatigue drain.
Today, only a few known Kingpins are alive adding up to a total of 4 out of 12. These are the four only known to Humanity and the Combine to date:
Tyrant - A deceptive and manipulative Kingpin that rules over one of the largest groups of Xenian creatures on Earth. Instead of using his armies to attack, he generally allows them to stay wild on Earth while he is off to trick the next group of humans, start some oddball cult or even trick Vortigaunts into helping him gain more authority and power.
Despot - Deranged and violent, it chooses to remain in Xen for the time being and only visit Earth on the rare occasion. So far it has managed to out maneuver the Combine and maintains a safe distance- while choosing complete insanity aggression tactics over any strategic moves. Its unpredictability gives it an edge in survival.
Lurker - More distant that other Kingpins and prefers being alone; but certainly likes to keep himself a mystic entity. The lurker generally avoids contact an watches from afar. But it is known they are on Earth with minimal sightings.
Warmaster - Cynical and completely aggressive. Also known to be mostly within Xen and not Earth, it choose to rage guerilla wars with the Combine trying to slow their progression in taking over Xen entirely and using the fragmented landscape to its advantage. Naturally it is a warmonger and not much else is known about its status.
Of course, the dead Kingpins consist of the Grandmaster who was Strategic and wise, the Vanguard brave and courageous, the Patriarch a powerful and zealous one, Aegis durable and stalwart, Ghast venomous and secretive, Voidborn horrific and corrupt, Missionary was honorable and selfless, and finally the Overseer who was efficient and productive in his role.