Demon (Doom)

"Demon" is the term applied to any species native to Hell, although they may not necessarily need to originate from there. During their expeditions into Hell, the Union Aerospace Corporation (UAC) discovered a wide variety of species residing in Hell which were collectively dubbed Demons. While sapience and general intelligence varies between species of Demon, they are shown to be extremely aggressive against all forms of life, including each other on occasion, but ruled by a currently unidentified entity whose voice and testimonies are heard by the being known as the Doom Slayer. (Whether this is the Mastermind later fought by the Doom Slayer, an entirely different being or even the devil himself remains unclear).

History
Little is known about the history of the Demons or even their home-dimension, despite its common reference in various religions, although the Demons have been shown to be capable of accessing other dimensions beyond their own and forcefully integrating them into Hell. The earliest recorded record of the Demons references a being known as Davoth, also known as the Dark Lord. Davoth was the ruler of Hell and Assembled the Demon hordes through conquering other worlds and corrupting their native denizens, transforming them into new forms of Demon. Eventually, Davoth was defeated by the Father, and his soul and essence were contained within a life sphere.

On the world of Argent D'nur, the native Night Sentinels encountered  an enigmatic Human whom they knew only as 'Doomguy.' A group Sentinel soldiers found him alone and wounded while on patrol, madly ranting about 'Demons everywhere' and how he 'must kill them all.' Although he was initially made to fight with other malcontents within the coliseum of Sentinel Prime, the Doomguy's ravings caught the attention of the Maykrs; the angelic species who once served the Father and was worshipped by the Sentinels. At the command of their leader, the Khan Maykr, the Doomguy gave testimony about the Demons, what he knew of them and his experience in fighting them (This heavily implies the Doomguy is in fact the protagonist of the Original DOOM, DOOM II and DOOM 64, having chosen to remain in Hell after fighting off a third demonic invasion in order to prevent further incursions).

Shortly after the Doomguy's arrival, the armies of Hell invaded Argent D'nur. Despite their initial immense losses, the Sentinels eventually gained an advantage after the Doomguy was empowered by Samur Maykr through the use of the Divinity Machine. This process granted the Doomguy superhuman strength, speed and durability. He quickly became a revered champion of the Night Sentinels, who dubbed him the 'Doom Slayer.' With the Slayer leading their armies, the Sentinels began to regain ground from the armies of Hell. During this war, the Sentinels learned of Argent energy, an otherworldly essence within every Demon which fuelled their powers and even gave them life. They began to harvest this energy from their fallen enemies, creating new and extremely powerful weapons that further granted them the edge.

Eventually, the Night Sentinels launched a counterattack into Hell itself. During this incursion, they discovered a disturbing truth about Argent energy. It was, in fact, converted from the souls of those conquered by the Demons. Tortured and twisted into madness and hopelessness, these victims would have their souls drained from their bodies and converted into Argent energy to maintain and empower the Hell dimension, while the body is transformed into a new Demon. The Sentinels are forced to conclude that the Demons themselves are in fact past victims of this process, having been conquered by Hell and transformed to join its hordes. Furthermore, the Sentinels also discover a pact shared between the Demons and the Maykrs. Having discovered that Argent energy could prevent the Maykr's transfiguration process, believed to be a transformation feared by the Maykrs, they desired more Argent than the Sentinels could provide in order to maintain their immortality. They offered to help the Demons find new worlds to conquer and new species to corrupt, and they would receive a steady flow of Argent in return for their service. This revelation lead to division and civil war on Argent D'nur, between those who remained loyal to the Maykrs and dependent on Argent energy, and those who rejected both.

Through the Maykr's betrayal, the war turned to the Demons' favour. The Doom Slayer led a team of Night Sentinels to Hell in the hopes of destroying their sources of Argent, but they were betrayed by the Deag Council, a trio of Sentinel priests who served as emissaries between the Sentinels and Maykr's. Remaining loyal to the Maykr's they sealed the portals and left the Night Sentinels stranded in Hell. One by one, they were slaughtered to the last by the endless Demon hordes. One of them, now known as the Betrayer, was contacted by the Demons, offering to resurrect his late son in exchange for the Elemental Wraiths; the original godly entities the Sentinels once worshipped before first contact with the Maykrs. Driven by grief and hopelessness, the Betrayer provided the Demons what they needed in order to capture and corrupt the Wraiths, and his son's soul was used to create a unique, extremely powerful Demon known as the Icon of Sin. Before long, Argent D'Nur had fallen, the remaining Sentinels were corrupted and the Maykrs searched for new worlds to offer the Demons.

Since the fall of Argent D'Nur, the Doom Slayer continued his unending killing spree against the Demons. As legions upon legions of Demons were slain by the Doom Slayer, a colossal Demon known as the Titan challenged him, only to be killed by his hand. Fuelled by unquenchable rage and bloodlust, the Doom Slayer was equipped afterwards with the Praetor Suit given to him by an unknown individual (The Demon recorded in the Slayer's testimony refused to identify them), enabling him to heal his wounds through the absorbing of Argent energy from physical contact with Demons, typically while tearing them apart. Fearing the threat of mass extinction, the Demons lured the Doom Slayer into a trap, collapsing one of their blood temples on top of him and sealing him inside a sarcophagus, marking it with their rune identifying him to warn all Demons of what is trapped inside and that he must never be released.

At some point in the future, the Union Aerospace Corporation (UAC) established a research colony on the planet Mars, where they discovered Argent Energy, presumably from the underground Sentinel colony of Hebeth beneath the planet's surface. Discovering the power output provided by Argent energy, the UAC proceeded to harvest it and soon resolved an energy crisis Earth was suffering from. In order to harvest more Argent, the UAC began to deploy expedition teams into Hell itself. Discovering the varied and aggressive species residing in Hell, the UAC began capturing Demons and returning them to Mars for further research, intrigued by this discovery of alien life. However, one of the UAC's researchers, Olivia Pearce, was contacted by the Demons and, formed an agreement with them. She proceeded to convert almost the entirety of the facility's workforce into a demonic cult, believing Argent energy and the Demons to be Humanity's salvation.

Suspicious of his former protege's disturbing experiments, including deranged experiments on Human and Demon test subjects, Samuel Hayden, the CEO of the UAC, embarked on an expedition into Hell and discovered the Doom Slayer's sarcophagus. After learning about the Slayer, Hayden had the sarcophagus transferred back to Mars in case his suspicions of Dr. Pearce were correct. Upon discovering the Slayer and fearing the possibility of failing the Demons, Pearce overloads the UAC's Hell-Portal and unleashes a massive burst of Argent Energy across the facility. The captive Demons are released and all Humans present in the facility are killed or mutated into zombie-like creatures. As he had long since transferred his mind into a robot body to survive a terminal cancer, Samuel Hayden survived this event. Fearing the possibility of the Demons spreading beyond Mars, Hayden releases he Doom Slayer from his confinement. Despite their reluctant alliance, The Slayer and Hayden fail to prevent Pearce from opening a portal to Hell, enabling an army of Demons to spill out onto the red planet. Although the Doom Slayer fought and slaughtered countless Demons, including the Spider Mastermind responsible for the invasion, he was betrayed and teleported to an unknown location by Hayden, who intended to continue research and production of Argent energy for Human use.

Some years after the incident on Mars, the Demons launched an invasion of Earth. This invasion was catalysed by the Deag Council, having infiltrated the UAC and using their resources to summon the Demon hordes to Earth. By the time the Doom Slayer arrived on Earth, 60% of the planet had already been conquered. The Deag Council had enacted a blood ritual that was gradually corrupting Earth, transferring it into Hell and terraforming it into a more suitable environment for the demons. In order to prevent this, the Slayer hunted down and assassinated the Deag Council, all the while waging a one-man war against the Demons and allying with Samuel Hayden once again. Throughout his mission, the Slayer is contacted by the Khan Maykr, who had evidently chosen the Human race as the Maykrs' next offering to the Demons in accordance with their pact. After the Slayer killed all three members of the Deag Council, the corruption of Earth is halted and the Demon invasion is doomed to failure. As a last resort, the Khan Maykr decides to unleash the Icon of Sin to destroy the planet and complete Earth's corruption. To that end, the Slayer fights his way through the Argent processing facility within the Demon city of Nekravol and gains access to the Maykr homeworld of Urdak. The Slayer locates and destroys the heart of the Betrayer's son, freeing his soul and breaking the Khan Maykr's control of the Icon of Sin. As the colossal Demon teleports to Earth, the seal preventing the Demons from accessing Urdak is broken. Taking it as a sign that the pact had been broken, the Demons proceed to invade Urdak. The Slayer confronts the Khan Maykr and kills her before returning to Earth, leaving the Maykrs at the Demons' mercy. Upon his return to Earth, the Slayer faces and slays the Icon of Sin, ending the invasion and saving Humanity.

Some time after the Demon invasion, the Slayer tracks down Samur Maykr, the renegade Maykr who empowered him on Argent D'Nur, to an undersea UAC facility. It is revealed that Samuel Hayden himself was in fact Samur Maykr, having assumed a Human identity in order to infiltrate the UAC and use them to release the Slayer from captivity in order to aid in his rebellion against the Khan Maykr's pact with the Demons. He commissions the Slayer's aid in locating the life sphere containing the essence of the Father, in the hopes of restoring him and rebuilding Urdak in order to restore balance to the universe. However, the Slayer defies this plan and destroys the Father's life sphere, instead taking the essence of the Dark Lord. The Slayer returns to Urdak, now under Demon control, in order to resurrect Davoth, only to destroy him entirely and seal Hell and the Demons from the rest of the multiverse forever. After defeating Samur Maykr in combat, the Slayer resurrects and confronts the Dark Lord, who assumes the Slayer's form.

Upon Davoth's manifestation, the Slayer immediately attempts to kill him, but fails due to defensive measures in Urdak's Luminarium preventing any form of bloodshed. Understanding that neither of them could kill the other at this time, Davoth challenges the Slayer to face him in Immora, the capital city of Hell, before travelling there himself via portal. The Slayer proceeds to return to Argent D'nur in order to acquire the Sentinel Crystal he required to travel to Immora, during which time he activates a sacred beacon which alerts the Night Sentinels to his intentions. Afterwards, the Slayer returns to Earth, now reclaimed by the Human race in their ongoing efforts to purge the remaining Demons left over from the invasion. The Slayer fights his way to an ancient portal being studied by the Humans and uses it to travel to Immora, where he is greeted by a massive army of Demons. However, he is joined by an army of Night Sentinels, led by Commander Valen, who engage in open war with the Demon hordes. The Slayer infiltrates the city and pursues Davoth to his throne room, where they proceed to fight in single combat. During their battle, Davoth reveals that he himself was the true creator of the universe, the ancient god responsible for creating Humans, Maykrs, Sentinels and all forms of life. The Father admits to the Slayer that Davoth was telling the truth, which prompts the Dark Lord to reveal that the Father betrayed him and imprisoned him in the dimension that would become Hell, resulting in the corruption of all that lived there into the Demons, whilst the Father was credited for the creation of all things. Despite this revelation, the Slayer saw no reason to spare Davoth and continued to fight. Eventually, the Slayer emerged victorious and slew the Dark Lord. Upon his death, Hell was sealed from the rest of creation and every Demon outside of it simply disintegrated. However, due to his superhuman power stemming from Argent energy, the Slayer collapsed into a coma. He was then sealed inside a sarcophagus by the other ancient gods and hidden within the sanctuary of the life spheres, where he would remain dormant until a time he was needed once more.

Variants
Possessed/Zombie - Humans corrupted by exposure to Argent energy, Zombies are mindlessly hostile to the living, but are easily killed. Zombies are slow moving and extremely unintelligent, serving as little more than cannon fodder. The corruption process seems to effect individuals differently depending on internal and external circumstances. Humans corrupted in this manner while wearing explosive materials, such as engineers or mechanics, effectively become walking bombs, whereas corrupted soldiers retain their agility and ability to utilize firearms but also boast increased muscle mass.

Mecha-zombie - Zombies enhanced with cybernetic modifications. They are noticeably more durable than standard Zombies and are equipped with mechanical claws and an arm cannon.

Carcass - Essentially a support robot built around a mutilated corpse. The Carcass is lightly armoured and primarily acts to project energy shields around Demons.

Unwilling - Zombies which have been transferred to Hell, Unwilling are essentially a more skeletal version of Possessed and behave identically to them. Unwilling are used by the Demons as slave labor and cannon fodder.

Imp - The most common species of Demon, Imps are thin and roughly the size and shape of a Human. Although quite weak in terms of durability and damage output, Imps are capable of channeling Argent energy into their hands, producing a ball of fire which they can throw at their enemies. This fireball may also be charged for increased damage. Imps are also capable of scaling walls, allowing them to attack their foe from any vantage point.

Gargoyle - Originally from Argent D'Nur, Gargoyles resemble humanoid bats with blades forcibly grafted into their arms. They are capable of flight, spitting toxic projectiles, but are equal to Imps in terms of threat level.

Prowler - Believed to be an evolved form of Imp, the Prowler is faster and stronger and possesses the ability to teleport at short distances. While Imps tend to fight in large groups, Prowlers are more solitary hunters.

Hell Razer - A Demon believed by the UAC to be host to a parasitic lifeform, the Hell Razer is armed with a chitinous growth in it's right arm which fires a continuous beam of argent energy. They also behave almost identically to Possessed soldiers which, along with their appearance and theorized origin, implies they may be a variant of Unwilling.

Pinky - A large feral Demon dubbed Pinky by the UAC, due to the other species' native to Hell having no name for it, Pinkies are extremely aggressive when faced with prey, recklessly charging at it while using the armor growing around its face as a battering ram to do so. The rear end of the Pinky is fully exposed, providing a weak spot for its enemies to exploit.

Arachnotron - After the Doom Slayer killed the Spider Mastermind, the UAC procured its remains and used them to clone numerous miniature duplicates of it. When the Demons invaded Earth, the UAC lost control of their cloning facility, which continued to automatically produce more Arachnotrons. These brain-like creatures are outfitted with an Argent plasma turret and explosive launchers.

Hell Knight - A huge brute bred purely for combat, the Hell Knight, while lacking the agility of Imps or any means of ranged combat, is extremely durable and boasts incredible strength, capable of shrugging off most weapons fire, Hell Knights will produce damaging shockwaves through smashing their fists into the ground, stunning their opponent.

Dread Knight - During the Demon invasion of Earth, the UAC attempted to enhance the Hell Knight through cybernetic augmentation. Dread Knights are these upgraded Hell Knights, boasting armor plating, energy blades mounted on their arms and neural implants that maintain their perpetual rage.

Summoner - Believed to be an evolved form of Imp, Summoners are capable of levitation, short-range teleportation and firing blasts of argent energy capable of killing a Human in a single burst and possibly converting them into Possessed. Summoners are named for their most prominent ability; teleporting other Demons from Hell into the reality they are currently present in to serve as reinforcements.

Spirit - Resembling an ethereal Summoner, the Spirit's threat lies in its ability to possess other Demons and enhance their combat capabilities. Only the Microwave Beam modification for the UAC Plasma Rifle is known to destroy Spirits. Spirits are, in fact, the souls of deceased Summoners condensed into a non-physical form.

Cacodemon - A large spherical Demon which is capable of flight and firing psionic blasts from it's mouth in order to immobilize prey for consumption. Cacodemons appear to be quite volatile, as puncturing their singular eye seems to cause them to explode.

Spectre - During their experimentation on Demons, the eye of a Cacodemon was transplanted into a Pinky, somehow causing it to become invisible. After the first Spectre escaped and returned to Hell, its descendants maintained this invisibility. Apart from this, they behave identically to Pinkies.

Revenant - Not quite a true Demon, Revenants are former Humans horrifically mutated and cybernetically modified by the UAC as part of a military experiment. Despite their origins, Revenants seem to be recognized as Demons by the denizens of Hell and are accepted into their ranks as such. Revenants primarily attack via shoulder-mounted rocket launchers and escape retaliation with their jetpacks.

Mancubus - A massively obese Demon outgrowing it's own natural armor, the Mancubus attacks its prey with a pair of organic flamethrowers in place of arms. Due to their diet of rotten meat, Mancubus innards have been made volatile and so puncturing the stomach can cause fatal rupturing. In their experiments, the UAC attempted to weaponize Mancubi by converting their flamethrowers into a sort of long-range plasma cannon. Unfortunately, the Cyber-Mancubus maintains its loyalty to Hell and continues to outgrow its UAC-issued armor, making them stronger than a natural Mancubus. During the invasion of Earth, a different subspecies of Mancubi are seen with mechanical arm-cannons instead, while the Cyber-Mancubi are adorned in armor that actually fits them.

Lost Souls - Appearing to be a flying horned skull, Lost Souls display extreme aggression to anything they come across through charging at high speeds at their prey. Although Lost Souls are killed upon colliding with their target, UAC research has stated that they do so to take a 'host.' Lost Souls are believed to be the remnants of those who escaped the Argent conversion process.

Baron of Hell - boasting twice the strength and size of the Hell Knight, the Baron of Hell is a massive horned beast capable of producing and throwing argent plasma at any enemies it is unable to tear apart with it's bare hands. Due to similarities in their body structure and the Baron's apparent authority over Hell Knights, Barons of Hell may in fact be an evolved form of Hell Knight.

Cyberdemon/Tyrant - During their expeditions into Hell, the UAC recovered the remains of an extremely large Demon unlike any they had previously identified. As the Mars research facility became taken over by a Demon-worshipping cult, the giant cadaver was reanimated with cybernetic technology. The Cyberdemon was powered by an argent energy core in place of a heart and its left arm replaced with an energy cannon. During the invasion of Earth, a weaker variant of the Cyberdemon was fielded known as Tyrants. These Demons behave similarly to the original Cyberdemon but are much weaker. Tyrants reportedly serve as wardens within the Demons' Argent processing facilities and slave camps.

Parasite - In their natural state, the Parasites appear to be small leech-like creatures. However, they are capable of operating organic mech-like constructs in combat, forming the Hell Guard. Hell Guard are extremely durable and are capable of projecting various energy blasts and shields from their maces.

Spider Mastermind - Believed to have been the mastermind behind the Demonic invasion of Mars, this Spiderdemon was reborn in physical form. After possessing a Human host, Olivia Pearce, the fusion of Human and Demon resulted in what appeared to be a giant brain-like creature housed within a spider-like weapons platform.

Doom Hunter - Originally a race of indigenous to Earth known as Agaddon Hunters, these beasts lived during the time of dinosaurs and were rendered extinct by the Doom Slayer and Night Sentinels. However, the UAC had since excavated their frozen remains and reanimated them through extensive cybernetic reconstruction. The Doom Hunter is protected with energy shields and armed with a powerful arm cannon, chainsaw and missile launchers mounted on its hover-sled. Despite being from Earth, they bear demonic appearances, implying some sort of connection. It is also unclear what they evolved from.

Marauder - Former Night Sentinels who remained loyal to the Maykrs after their betrayal was exposed. They were since enhanced with the Divinity Machine, mutating them into demonic reflections of the Night Sentinels they once were. Marauders are armed with Argent axes, Super Shotguns and a ghostly wolf and are capable of challenging the Doom Slayer in single combat.

Arch-vile - Powerful Demons capable of channeling Argent energy in a variety of dark powers. Similar to Summoners, albeit several times tougher, Arch-viles specialize in summoning large groups of Demons and enhancing them in battle. When threatened, the Arch-vile can teleport, project shields or blast columns of Argent energy at their target. Arch-viles are described as 'descending from the eldest race of Demons', implying they are considered nobility among the Demons.

Titan - Massive Demons named due to their immense size, rivaling skyscrapers in height. Titans are typically utilized as slaves by the Demon horde, serving as beasts of burden or wreaking mass destruction anywhere they go.

Icon of Sin - An impossibly powerful Demon manifested from the soul of the Betrayer's son, the Icon of Sin is considered a specialized form of Titan, boasting various Argent-based powers and summoning capabilities. The Icon is adorned in armor of Maykr design and can only be killed using a Crucible Sword.