Demons

Demons are a supernatural species of creature, consisting either of dead human sinners or native citizens, that inhabit Hell.

Description
Demons are a catch-all term for any entity that resides in Hell. Demons can range from unique and sapient species, such as Imps or Succubi, to non-sapient fauna species, to more disparate and non-singular groups such as Sinners, which represent less of a unique species and more of a disparate collection of incompatible mixtures of different entities. Demons come in all shapes and sizes.

Their physical forms typically have characteristics associated with the human body, except for having human ears and sometimes lack of a nose.

Culture
Demon society follows cultural lines similar to that of humanity in some regards. There are laws that are upheld, facilities that provide goods and services (shops, news stations, bars, etc.), and emergency services such as fire departments.

Technological developments in Hell appears to mirror that of Earth, albeit with a twisted and demonic influence in the design outcome. However, some of Hell's technological developments, specifically weapons technology, have also been influenced and inspired by angelic technology to some unknown degree, which changed the face of Hell combat and lead to the development of "blessing" Hell weapons (such as the Carmine Crafted Blessing-Tipped Rifle used in The Harvest Moon Festival), similar to Exorcist weaponry, that can kill even Demon Royalty.

While demon society is very diverse, it can be somewhat divided into two distinct groups in Hell: Sinners and Hellborns.

Sinners are unable to leave the ring of Pride, of which Hell has seven rings, for reasons or methods unknown, and thus are entirely present only in that ring. Hellborn, which applies to all demon species born there, can be found in all seven rings of Hell, and can freely travel across any and all of the rings.

As Hellborn demons were never human, nor did they ever live on Earth, they have no experience of humanity or the human world. In spite of this, Hellborns make ready usage of human inspired/derived technology and cultural norms.

Demons of Hell are governed by a crude form of hierarchy, in which one's position in the hierarchy is determined purely by the strength of the individual, and it is dominated by Lucifer, a Fallen Angel, above all other demons (even Satan and Beelzebub). This hierarchy is roughly divided into tiers; going top-to-bottom, it is as follows:


 * Lucifer - The King of Hell
 * Charlie Morningstar - Heir apparent to Hell's throne
 * The Seven Deadly Sins
 * The Demons of Ars Goetia, which includes Stolas
 * Overlords - Demons who wield considerable power
 * Sinners - Demons who were once humans on Earth
 * Hellborns, such as Succubi and Incubi, among other unknown demon species of Hell
 * Lowest class Hellborns, such as Imps and Hellhounds - The bottom of Hell's society

The existence of the tiers demonstrate exceptions to the hierarchy system. The first being that a demon's status is treated variably. For instance, Charlie, despite being the second-highest-ranking demon, is not respected by the populace due to their spiteful climate. Rather, respect is dependent on the power and intimidation of one's character, like in Lucifer's case.

Sinners are unique in that they can elevate their status by accumulating powers, which they receive by making deals, soul dealing, or even taking it by force. These beings, colloquially known as Overlords, could theoretically rival higher-ranking Hellborn demons or even royalty of Hell, although the royalty would still be considered above them. Overlords typically obtain or enhance their powers by making deals with other demons, as well as dominating them in battle and taking in their dark energy.

While there has never been mention of demons practicing any form of spiritualism or religion, the existence of a sign that says "Satan Bless" that can be seen being held by a homeless demon in the pilot episode of "Helluva Boss" coupled with demons' tendency to swear by Satan's name in lieu of God, implies some sort of belief system or revering attitude at least with Satan.

Additionally, VivziePop has mentioned that they also celebrate Christmas but instead of Santa Claus, they eagerly await Krampus' arrival.

Language
Demons are known to possess their own languages, similar to humanity, as revealed when Charlie is stated to be fluent in every demon language she has learned while growing up. However the majority of demons seemingly speak a form of English, which has been referred to as "Satan's plain English". Humans are capable of understanding and conversing with demons and vice versa with no apparent difficulty.

The only other non-English language that has been communicated in either show, so far, has been Spanish by Vaggie.

Appearance
Demons tend to have an overarching theme to their design, typically hellborn species have very consistent appearances and biological designs according to their species, whereas Sinners can have extremely diverse appearances. Sinners can resemble animals (some more so than others), objects (such as Vox appearing as a television, some gun-esque demons or even inanimate objects such as couches), humanoid, and more, appearing in a wide array of colors, appearances, sizes, and structures based on what creature their character is based on. According to Vivziepop, hellborn demons appear more monstrous, whereas demons that appear more humanoid-looking, such as Lucifer and Charlie, are actually quite rare.

As some sinners can manifest in non-biological forms, such as televisions, furniture and akin, it is possible that some form of magic can allow these sinners to function in spite of the lack of a biologically functional body. Hellborns are born with fully functional biological bodies.

Some demons, particularly sinners and some Hellborns, are able to alter parts of themselves at will, such gaining an extra or new set of appendages such as extra pairs of eyes, horns, limbs, or simply can enhance parts of their default form's body parts (such as the rest of Charlie's teeth becoming pointed fangs).

Mortality
All demon species are vulnerable to physical trauma, however certain groups are immune to death by conventional means. Sinners, and Hellborns who are part of the "Demon Royalty" such as Stolas, can only be killed by Exorcist-based weaponry, typically wielded by Exorcists. Imps, which are a non-royal hellborn species, can be killed by conventional weapons and means, in addition to exorcist weaponry, although this has yet to be shown to be the case for all non-royalty hellborn.

When hit by an Exorcist's weapon, it results in the "final death" of the demon, and the demon's body is "killed off", with the remaining dark energy that's left in the soul is left to wander into inanimate objects in its surroundings, which explains why some things such as regular furniture have functioning eyes.

Lifespan
It is suggested that demons may not be biologically immortal, suggesting that they can still die from certain causes, such as old age. Sinners stop aging when they arrive in Hell (ex: Alastor dying in his 30s will remain 30 years old for the rest of eternity in Hell). As for Hellborn demons, they are proven to age, although the rate and overall longevity is unknown. However, in the case of the royal family, they are implied to age far slower than humans (as shown in the royal family portrait of 1875), maturity and intellect-wise, but show little to no changes when it comes to their physical forms.

Demons are able to consume food and similar sustenance, suggesting they need the intake in order to survive, which is supported by the Wrath Ring's essential role in food provision. It is unknown if sinners also require food to survive.

Abilities
Most, if not all, demons share the following traits:
 * Demon transformation: Some demons have demonstrated the ability to transform into larger, stronger, and more demonic alternate forms. So far, Charlie, Helsa, Katie, Alastor, Verosika, Stolas and the Succubi demons have been capable of this. According to artist Faustisse, all demons can transform when enraged or when in combat.
 * Longevity: Demons, at least for Sinners, do not die of old age and most of the other natural causes that kill humans. However, they can still be killed once they are hit with any of the Exorcists' weapons, or if they have been infected by Hell's own diseases and the like. This trait appears to be exclusive to certain demon types, since Imps are capable of dying and aging naturally, while higher-ranking demons like Charlie have been alive for centuries.
 * Human disguise: As revealed in "Spring Broken", certain demons are able to shapeshift their appearance into a human lookalike in order to infiltrate the living world. So far, only Hellhounds and Succubi have shown to possess this trait. It is unknown if other hellborn or sinners have this ability. This ability is not perfect, as some demonic characteristics can still be identified, such as eye color or ear shapes.
 * Unique abilities: Demons have a wide range of abilities, the types of which are occasionally attributed to certain Hellborn species, such as the succubi's ability to manipulate hormones. For Sinners, they possess abilities that vary for every individual, depending on their demon form.
 * Fire resistance: It is revealed in the first episode of Helluva Boss, Murder Family, that imps are resistant to flames and cannot be burned.
 * Retractable limbs: Angel Dust, a Sinner, is shown to have three sets of arms. The third set, he's able to retract into his body.
 * Flight: Husk, a Sinner, is capable of flight due to his wings.

Reproduction
As mentioned before by Vivziepop, Sinners cannot reproduce, although Hellborns can. In the case of Charlie, her birth is yet to be explained as Lucifer is the only known Fallen Angel in a relationship with Lilith, a demon whose origins are unclear.

Sinners

 * Employees of the Hazbin Hotel
 * Vaggie
 * Niffty
 * Husk
 * Sir Pentious
 * Cherri Bomb
 * Mimzy
 * Baxter
 * Mrs. Mayberry
 * Anchormen of 666 News
 * Katie Killjoy
 * Tom Trench
 * Angel Dust's family
 * Angel Dust
 * Arackniss
 * Angel Dust's father
 * Founders of Lyle-Loopty Robotics
 * Lyle Lipton
 * Loopty Goopty

Hellborn Demons

 * Charlie Morningstar
 * The von Eldritch family
 * Frederick von Eldritch
 * Bethesda von Eldritch
 * Helsa von Eldritch
 * Seviathan von Eldritch

Demons of Ars Goetia

 * Stolas' family
 * Stolas
 * Stella
 * Octavia
 * Andrealphus
 * Paimon

Hellhounds

 * Loona
 * Vortex

Imps

 * Blitzo's family
 * Blitzo
 * Barbie Wire
 * Tilla
 * Moxxie
 * Millie's family
 * Millie
 * Lin
 * Joe
 * Sallie May
 * Millie's unnamed brothers
 * Wally Wackford
 * Striker
 * Fizzarolli
 * Stolas' family butler

Succubi

 * Verosika Mayday
 * Verosika's posse
 * Josh
 * Kat
 * Milky
 * Kiki
 * Apple
 * Coco
 * Ace
 * Dia

Baphomets

 * Lavender
 * Paradise
 * Waxi
 * Tim
 * Mona
 * Pee & Wee

Overlords

 * Alastor
 * Rosie
 * The V Triumvirate
 * Vox
 * Velvet
 * Valentino

Artificial Demons

 * The Egg Bois
 * Robo Fizz

Wildlife

 * Pig Demons
 * Fat Nuggets
 * Horse Demons
 * Bombproof
 * Insect Dog-like Demons
 * Queef (non-canon)
 * Cat Demons
 * KeeKee

Others

 * Charlie's parents
 * Lucifer
 * Lilith
 * Mammon
 * Asmodeus
 * Crymini
 * Razzle and Dazzle
 * Summer

Trivia

 * If a demon dies in Hell, the dark energy within them wanders off and possesses random everyday inanimate objects such as furniture and tools, which explains why some of the things seen in the background and such have functioning eyes.
 * So far, male and female demons exist in terms of demon culture's gender dynamics. In the case of Hellborn demons, however, it is unconfirmed if some species possess gender-based names or share a gender-neutral common name. For instance, in Abrahamic religion, a lust-based demon is traditionally known as a succubus for females and an incubus for males, respectively, albeit this distinction has lessened over time. Succubi and incubi exist in Hell, but the male and female lust demons that have appeared together, such as Verosika's posse, are collectively labelled succubi, seemingly excluding the term "incubus".
 * Shades of gender identity are also hinted at, with Sallie May being the first demon confirmed to be transgender.
 * Since demons theoretically can not die via natural causes, such as illnesses and overdosing, they are able to consume amounts that would be lethal to humans without any risk of dying.
 * This is shown in both Angel Dust and Husk as both are able to consume vast amounts of drugs and alcohol without any threat of death.
 * This does not mean, however, that there are no negative side effects, as Loona makes clear that demons can still get hangovers.
 * According to character designer Jane Walker, the goat-like demons that appeared at Ozzie's belong to a hellborn species called Baphomet.