Hell Knight

Among the Demons of Hell, Hell Knights function as an elite warrior caste, boasting immense strength, authority through brutality and a surprising degree of loyalty to their superiors.

Biology
While they were initially encountered as hulking, tan-skinned satyr-like creatures, nearly identical to a breed of Baron of Hell in everything from appearance to attack power, only lacking the same level of durability, modern Hell Knights seem to resemble the Imps beneath them, albeit much larger and more muscular, with predominantly brown exoskeleton-like armor and a head resembling an exposed skull. Unlike Imps and satyr Hell Knights, skeletal Hell Knights have no ranged attack capabilities, instead channeling Hell Energy into their fists to enhance their attacks. However, another variant of skeletal Hell Knights has been able to create and throw fireballs. While they initially had eyes that were barely visible, what appears to be a more evolved strain of skeletal Hell Knights has clearly visible green eyes, and snowy white armor. While their level of sapience is unknown, the UAC have hypothesized that in addition to serving as front-line warriors and enforcers among the Demon hordes, Hell Knights also serve as gladiators. They are also known for their innate regard for hierarchy, readily serving their superiors on their own free will, a unique trait among demons. They are also known to gain great satisfaction from war and destruction. Interestingly, the Baron of Hell has been described by the UAC as the 'highest demon among the order of the Hell Knights.' Between this description and the extremely similar appearances of their original incarnations, it is implied that Hell Knights may evolve to become Barons of Hell at some point in their lives. All Hell Knights are highly resistant to various forms of weaponry.

Dread Knight
During the Demon invasion of Earth, the UAC cult attempted to enhance the Hell Knight through cybernetic augmentation. Hell Knights subjected to this process are known as Dread Knights, clad in grey armor covering their heads, shoulders, forearms, and abdomens. In addition to armor plating grafted into their bodies, they also wield energy blades mounted on their arms and neural implants keep them trapped in a state of permanent rage, providing relief in the form of dopamine only during the act of killing. The augmentation process also colored their skin light brown.

History
The Hell Knights came from a demonic dimension called Hell. Throughout an unknown period of time, various subspecies of Hell Knights arose, and during the first age of Hell, Hell Knights flanked a being known as the Great Serpent, until the Serpent was defeated by the Guardian. Hell Knights were then used as enforcers for other Archdemons, gladiators in the Hell arenas, and elite soldiers in interdimensional invasions, often fighting a race known as the Argenta, who were led by the Order of the Night Sentinels. The Argenta priests turned against the rest of the Argenta, siding with the Maykrs, who struck a deal with Hell for their mutual benefit. The Night Sentinels, along with their champion, an unnamed Human known only as the Doom Slayer, were trapped in Hell, where Hell Knights and other demons launched a relentless assault on them. Only the Doom Slayer survived, and continued to fight demons for eons, until he was finally locked away in a tomb on the surface of Mars within an unknown universe. In the future, when Union Aerospace Corporation (UAC) scientists were experimenting with teleportation technology on Phobos, they accidentally opened a rift to Hell. This caused a whole manner of demonic forces to come through the portal onto Mars' moons and the other bases. The demons brought destruction on the UAC bases and killed or possessed many UAC personnel, although they too were killed by a lone marine who ended the invasion by killing the commanding Cyberdemon, and the Spiderdemon above him. Not too much later, they made their way to Earth to continue their attack there. It was here that the single hero, the marine, slaughtered the demon hordes, including satyr Hell Knights, and later managed to close the rift between the dimension of Hell and the Earth itself by killing the Icon of Sin, sealing surviving Hell Knights away in Hell. The corpses of Hell Knights left on the Martian moons would later be revived by the Mother of All Demons, only for the marine to destroy them again. The marine then voluntarily remained in Hell to put down its threat forever, fighting hordes of demons alone, somehow going back in time and across dimensions, eventually becoming the immortal superhuman known as the Doom Slayer, the very one who had fought demons over eons. Some time in the future, in what appears to be another universe, a race of fireball-throwing skeletal Hell Knights was found by a UAC teleportation experiment team. Some specimens were brought to Mars for study. Hell Knights were among an invasion force that attacked a UAC Mars base, brought over by a Human cultist named Dr. Betruger. An unnamed UAC Marine fought his way through the Hell Knights and other demons to Hell, killing their Cyberdemon and stopping the invasion. At another point in the future, in what could be the same universe, skeletal Hell Knights without the ability to shoot fireballs were brought over to Mars by a growing faction of cultists within the UAC, led by Dr. Olivia Pierce. When the demons launched another invasion of Mars, the Doom Slayer was woken up, as the universe he was held in was the very one being invaded. Retrieving his armor and weapons, the Doom Slayer eventually fought Hell Knights, killing them and other demons, eventually killing the Spider Mastermind and stopping the invasion. Years later, in the same universe, a demonic invasion of Earth was launched at the order of the Khan Maykr, and Doom Slayer, who had been banished out to unknown regions of space at the end of the previous invasion, returned in an Argenta space station to combat the demons once more. A seemingly more evolved strain of skeletal Hell Knights were used, along with a breed of Dread Knights, Hell Knights cybernetically modified by UAC cultists, who fought alongside other demons against the Armored Response Coalition (ARC), Earth's current defense force, and UAC security forces not loyal to the cultists. Many were killed in Slayer's rampage throughout Hell, Earth, Mars, and Urdak. All Hell Knights remaining on Earth were gradually killed or otherwise banished after the death of the Icon of Sin. Slayer then utilized ARC resources to retrieve the life sphere of the Dark Lord in order to destroy it, killing more Hell Knights along the way. After reviving the Dark Lord, the Slayer returned to Earth to find a path to Immora, killing some Hell Knights remaining on Earth, and alongside Sentinel armies, killed more Hell Knights used by the Dark Lord in the final battle between Hell and the Slayer. All Hell Knights outside of Hell were destroyed when the Dark Lord was killed.

Appearances

 * Doom II (1994)
 * Doom 64 (1997)
 * Doom 3 (2004)
 * Doom (2016)
 * Doom Eternal (2020)
 * Doom Eternal: The Ancient Gods Part 1 (2020)
 * Doom Eternal: The Ancient Gods Part 2 (2021)