This list contains only those demons encountered in the story so far and will be added to as new ones are introduced.

Demon of Darkness

Name: Unknown     Fixation: Darkness    Demon Level: Lesser     Location: Bianca's Main Floor

The Red Demon

Name: Unknown     Fixation: Shame    Demon Level: Lesser     Location: Bianca's Second Floor

Succubus Maid 1

Name: Felola     Fixation: Loli Perversion    Demon Level: Lesser Succubus    Location: Bianca's Second Floor

Succubus Maid 2

Name: Jilysh     Fixation: Carnal Pleasure    Demon Level: Lesser Succubus     Location: Bianca's Second Floor

Succubus Maid 3

Name: Unknown     Fixation: Unknown    Demon Level: Lesser Succubus     Location: Bianca's Second Floor

Gargoyle Demon

Name: Unknown     Fixation: Knowledge    Demon Level: Lesser     Location: Bianca's Second Floor

This list contains only those demons encountered in the story so far and will be added to as new ones are introduced.

Stone Angels

A form of gargoyle that resembles a statue of an angel. Stone angels are typically set as guardians of cemeteries processing spirits from Christian areas of the Upperworld and ensuring they return to the ether in an orderly manner. 

Ghouls

Ghouls in habit cemeteries graveyards and anywhere dead bodies might be found. Once the spirit has dissipated into the Ether, the ghouls will consume the body to make room for the newly dead. Ghouls have the general appearance of a human but with canine faces. Their societies and general behavior also resembles the canine. One of the few monsters to exist in groups. Also, one of the easiest monsters to evolve into.

Swamp Monster 

Although, many variants of swamp monster exists in the Underworld, the only one so far encountered is Big Bertha. Big Bertha is a eighteen-foot long alligator like creature covered in thousands of tentacles of widely different sizes. Big Bertha patrols the lake on the edge of the Above Ground Cemetery and whose main duty is to ensure ghouls do not invade the swamp.

Prehistoric Rats

Living in the Fire Bog, prehistoric rats are massive predatory creatures that can weigh over two-hundred pounds when mature, have rows of voracious fangs, a back fin of serrated bone, and glowing green eyes. They have a natural resistance to fire and can even utilize it as a weapon by using the area's gas jets to light  themselves on fire and burn enemies when attacking. These rats serve to keep the Fire Bog mortal-free. The demon in charge of the bog has no love for mortals and made it inhospitable to keep them out, when they still came they, added the rats.

Within this stories universe it is possible for characters to evolve (or devolve). This is a general guide on how it works.

General Rules:

• The only natives of the Underworld are monsters and demons. These beings are born in the Underworld and serve to maintain it.
• "Mortal" is the common term for anyone who entered the Underworld through death. All people in the real world (Upperworld) enter the Underworld upon death.
• The most common state to enter the underworld as is a spirit. Spirits are disembodied beings confined to a cemetery that will dissipate in the Ether over time. 
• If a person has a significant amount of spiritual power when alive, they may enter the Underworld with more freedom (not confined to a cemetery) or even with a physical body. The exact circumstances depends upon a the amount of spiritual power the individual possesses.
• Any mortal may evolve (or devolve) into another type of being.
• A mortal may even evolve into a monster or a demon. Once they become a monster or demon they are no longer deemed mortal.
• The Underworld will attempt to push a mortal to one potential outcome or the other, and see that they return to the Ether or become a monster or a demon.
• A mortal does not have to evolve (or devolve), and may stay in the same state for all eternity.
• Evolution does not depend on experience or skill. It is entirely arbitrary and the result of outside forces (usually magic) effecting them. Although, it is possible for a mortal to manipulate these outside forces to enact a change to their benefit.
• Evolution does not need to be incremental. A mortal may ascend (or descend) to a new point on the evolutionary ladder by skipping many different intermediary stages. For example it is theoretically possible for a spirit to evolve into a lesser demon without going through any of the steps in between. Or more commonly, if a Revenant's body was destroyed they would devolve into a Spirit and not a Zombie, which is the next stage down.

Evolutionary Ladder:

1. Spirit (dead). An ethereal being usually confined to a cemetery to await dissipation back into the Ether. Spirits can not manipulate anything physically, and their memories get worse over time until they forget everything about their lives and their after lives. 
2. Zombie (undead). A reanimated corpse. Aside from their ability to think and move, zombies are little different than unanimated corpses. Their appearance is of the original living person with any of decomposition and rot that took place between death and reanimation. Zombies are limited in their dexterity, physical sensations, and emotions. They do not need to eat, drink, or sleep. 
3. Revenant (undead). Similar to zombies but with a working heart and respiratory system. They do not have any of a zombies limitations but will maintain the appearance of decomposition and rot (if any). They do not need to eat, drink, or sleep.
4. Preternatural Mortal (citizen). Preternatural mortals are the closest thing to living people in the Underworld. In appearance they are entirely human and are not afflicted by postmortem rot. They do need food, water, and sleep to maintain their bodies.
5. Supernatural Mortal (citizen). These are enhanced versions of preternatural mortals. They may not be entirely humanoid or may not be human at all times. They also may have a wide verity of special abilities. Requirements to maintain a supernatural mortal body varies. Vampires and werewolves are a couple of examples of supernatural mortals.
6.  Monster (native). There are many different types of monsters. Monsters are never entirely humanoid, but may be partially humanoid. Although, just as often, there is nothing human about them. All monsters have a function in maintaining the Underworld. Some examples of functions include: guardian (stone angel), sentry (swamp monster), and waste disposal (ghouls).
7. Demon (native). Demons are the rulers of the Underworld and every demon controls some portion of it. The size of the area of control depends on the demons rank. So, a lesser demon may rule over a single room, whereas a superior demon may rule over an entire region. The one exception is the arch demons, who are agents of chaos and attempt to undo the order imposed by their kin. Al demons are humanoid with the addition of horns and a tail. They may also posses other non-human characteristics such as wings, fangs, and unnatural skin or hair color. All demons have a primary fixation whether it be a sin, an emotion, a condition, or a trait. Some examples of fixations include: demon of lust, demon of darkness, demon of envy, demon of lost souls, etc...