Spiderdemon

Spiderdemons are highly intelligent non-humanoid demonic commanders.

Biology
Spiderdemons are large, usually sessile beings, resembling brains. They bear grey semi-humanoid faces with red eyes and sharp teeth. They appear to have either no nose or a very small and indistinct nose, and their features appear notably sunken, angular, wrinkled, and almost skeletal. Their bodies appear to be a giant brain, similarly to Kalibas' species, but the Spider Mastermind clones were known to have a skeletal structure within their bodies. Their essence is able to fuse with Humans, which can allow them to grow four partially organic crab-like legs, makes them far larger, and makes their features oddly appear more alien, with two split jaw components bearing extra teeth. The only visible organic limbs on an unmerged Spiderdemon are two spindly, near-useless arms present near their faces. Notably, their souls can survive long after death, which is what allows them to merge with Humans and regain an organic body. Their usual cybernetic chassis consists of a blocky "seat" with four mechanical legs, and an oversized chaingun on its underside. Spiderdemons are known to be very durable and highly intelligent, even able to psychically control other demons, even powerful demons such as Baalgars, but this may have been exclusive to the Spider Mastermind, which became the Dark Lord. The Spider Mastermind also bore a unique cybernetic chassis, which seemed to somewhat resemble the cybernetic exoskeleton worn by Dr. Olivia Pierce, and carried a powerful energy cannon on its underside. While Spiderdemons have been described as both male and female, there appears to be no visible distinctions between genders. Young Spiderdemons, often referred to as Arachnotrons, have light grey bodies and blue eyes, mostly resembling a far smaller version of the adult Spiderdemons, and are given similar cybernetic mechs with plasma cannons in place of a chaingun. The Spider Mastermind's genetic material was able to make smaller, Arachnotron-like clones of itself, although notably different from natural Arachnotrons. The exact method of Spiderdemon reproduction is unknown, as is the sapience of the Arachnotrons. The Spider Mastermind clones appeared non-sapient, but this may have been due to a modification or the cloning process being imperfect. The Spider Mastermind had red blood, possibly the result of fusing with a Human, while its own cloned Arachnotrons had blue blood.

History
Spiderdemons came from a demonic dimension known as Hell. They rose to commanding ranks in the invasion of the multiverse, like Tyrants and Arch-viles, and at some point in time, the demons either built or stole cybernetic technology that allowed the Spiderdemons to be grafted to a quadruped chassis. Their cybernetics allowed them both mobility and combat power, with one Spiderdemon, taking on the title of the Aranea Imperatix, rising especially high in the ranks. By the fourth age, the Aranea Imperatix became the Dark Lord, now known as the Spider Mastermind. In 2022, the Spider Mastermind, seeing that Union Aerospace Corporation scientists on Mars were testing teleportation technology that used Hell as a slingshot, organized an invasion force to conquer their universe, appointing a Cyberdemon as its commander. They pulled Deimos into Hell, with the Cyberdemon being put in control of the moon, while Phobos was assaulted by demons, being put under control of two Barons of Hell. A squad of Human US marines assigned to a UAC Martian base as security were sent to Phobos to retake it, but were almost completely slaughtered by the demons, leaving only a lone, unnamed marine. The marine fought his way through the base, singlehandedly capturing Phobos, taking the teleporter to Deimos, killing the Cyberdemon, and fought his way to the Spider Mastermind, who resided in the Hell city of Dis. The Spider Mastermind fought him, and was destroyed by the marine, allowing the marine to return to Earth. However, before it was killed, the Spider Mastermind had sent demons to invade Earth, assaulting the city that the marine arrived at and killing his pet rabbit, with command of the invasion being taken over by the Titan known as the Icon of Sin. As the marine fought his way through the invading hordes to the Icon of Sin, he killed more Spiderdemons who stood in his way, including young Arachnotrons. All surviving Spiderdemons were sealed away in Hell when the Icon of Sin was killed, although Spiderdemon corpses were later reconstructed on the Martian moons into undead Arachnotrons by the Mother of All Demons, granted heftier cybernetic chassis with dual plasma cannons, only to be destroyed again by the same marine. Although its body was destroyed, the Spider Mastermind's essence survived, and soon became the Dark Lord once more following the death of its successor, the Maledict. Hell texts began to refer to the Spider Mastermind as a being who is destined to join with its most loyal supporter, allowing it to be reborn. Meanwhile, in the Earth-realm, an opportunity for the Spider Mastermind's rebirth came in the form of Olivia Pierce, an aspiring UAC scientist and protégé of Dr. Samuel Hayden, who, unknown to Olivia or the Spider Mastermind, was the Human form of a Maykr Seraph named Samur. Pierce, who had become obsessed with Hell after a Hell artifact known as the Helix Stone began corrupting her mind, took up a position in the Argent Facility on Mars, which was a direct link to Hell. The exposure to Hell soon gave Pierce idiopathic scoliosis, forcing her to graft a cybernetic exosuit to herself, and prompting her to make a deal with the Spider Mastermind, offering to aid its invasion in exchange for curing her illness and giving her great power, like that of a god. To complete her new goal, she founded a faction of cultists made up of other UAC personnel, launching expeditions into Hell through the Lazarus Project, which she secretly repurposed to suit her desire of godhood. The cultists began taking demons to Mars, such as cyclopedic Mancubi, cybernetically modifying them into Cyber-Mancubi, and soon retrieved the corpse of a Baalgar. The Baalgar was revived with cybernetic enhancements, and possibly under the command of the Spider Mastermind, followed a cultist into a holding pen, where it was sealed in and killed the cultist. While the cultists created more cybernetic horrors, such as the Human-based Revenants, the Spider Mastermind ordered Pierce to secure the sarcophagus of the Doom Slayer, a superhuman being who had ravaged Hell for eons, who was in truth the same Human marine that originally killed the Spider Mastermind, who had voluntarily remained in Hell after killing the Mother of All Demons, somehow going back in time and across dimensions. Despite Pierce's efforts to keep the Doom Slayer's location secure, he was found by Samuel Hayden, who successfully retrieved the dormant Doom Slayer and kept him on Mars. The Spider Mastermind berated Pierce for her failure, but Pierce assured it that she would continue the plan regardless. To set the plan in motion, Pierce utilized the Argent Tower to open a portal to Hell, unleashing an energy wave from the Lazarus Labs that killed her own elite cyborg bodyguards and converted most of the personnel into possessed minions, while releasing all captive and modified demons from containment, who operated on the direction of the Spider Mastermind. The Doom Slayer was awoken, retrieving his weapons and armor, and fought his way through the corrupted Mars base to Hell, where he cut off Hell's main Argent Energy plant, The Well, by freeing the Elemental Wraiths that powered it. Olivia Pierce, who had escaped to Hell before the Doom Slayer could reach her on Mars, found her body continuing to deteriorate, and the Doom Slayer caught up to her within The Well. Pierce realized the Spider Mastermind never planned on giving her power, as a lightning strike has her body fuse to the soul of the Spider Mastermind, allowing the Spider Mastermind to regain a physical body, which made it larger, more monstrous, and with organic legs, although its whole body was still covered in cybernetics akin to the suit Pierce wore, and its armament was replaced with a more powerful energy cannon. The Spider Mastermind fought the Doom Slayer, but was unable to reach its full power level, being worn down by the Doom Slayer and forced to the ground, where the Doom Slayer used the BFG-9000 to blast the Spider Mastermind apart, killing it for good. However, the Doom Slayer was then teleported away by Samuel Hayden, allowing the remains of the Spider Mastermind to be retrieved by the UAC. No more adult Spiderdemons were sighted by the Doom Slayer or Humans after the Mastermind's death. The remains of the Spider Mastermind were used to create cloning plants, creating Arachnotron-like presumably non-sapient clones of the Mastermind, all fitted with a cybernetic chassis armed with an Argent Energy cannon and grenade launchers. The original purpose of this project is unknown, and could've either been another action of the cultists or an attempt to make the demonic monster into an asset they could control for their own defense. Whatever the case, the facility was soon overrun by demons during the Maykr-led invasion of Earth, but the AI in charge of the facility continued manufacturing Arachnotrons, now under the control of the demons. They were used by demonic forces during the invasion of Earth, but when the Doom Slayer returned to Earth with an Argenta war station, he soon ripped and tore through their ranks to eliminate the Hell Priests on Earth, destroying more Arachnotrons in Hell, Argent D'Nur, Mars, and Urdak. Arachnotrons aided the Icon of Sin during its attack on Earth, but after the Icon was killed by the Doom Slayer, all Arachnotrons left on Earth were destroyed or pushed back by a renewed Human resistance. Arachnotrons continued to fight the Doom Slayer as he made his way to the Hell city of Immora to kill the first Dark Lord, Davoth, organizing alongside Jekkadian Demonic Troopers, but were unable to stop him or the Night Sentinel army from breaching the walls of Immora. All Arachnotrons and Spiderdemons outside of Hell were destroyed when Davoth was killed.

Appearances

 * Doom (1993)
 * Doom II (1994)
 * Doom 64 (1997)
 * Doom (2016)
 * Doom Eternal (2020)