Demon Lord

The greatest denizens of the nightmarish dimension known as the "Heart of Darkness", demon lords were the higher beings who stood atop the group of creatures known as "Demons". Every single demon lord was a unique creature but they had a few traits in common: every single demon lord ruled over at least a single layer of the Heart of Darkness, was worshiped by hundreds if not thousands of demons, and had cults that spanned galaxies. These higher beings were among the more feared higher beings, for good reasons.

-From the "Dimensional Handbook: A Guidebook to the Universe"

Demon lords were a sort of higher being who ruled over minuscule parts of the chaotic-evil dimension known as "The Heart of Darkness". Like other higher beings, they were wiped out at the end of the mythic age under mysterious circumstances. 
At the moment, there is only a single demon lord in existence: Althos, the mysterious entity known as both "The Hungering Void" and "The Eternal Emperor". That said, he himself has plans to not be the only demon lord in existence in the near future, as he plans to convert at least one of his worshipers into a demon lord of obedience and servitude. 

Trivia:

• The first demon lord named in A Solitary God was Morthos, a demon lord who was known to have a massive cult possibly billions strong, composed almost entirely of dark elves.
• No two demon lords become demon lords in exactly the same way. Every time a layer of the Heart of Darkness is dominated it asks for something unique from the demon lord or would-be demon lord who seeks to dominate it.
• Demon lords are like deities in that when one becomes one they gain influence over a number of domains and subdomains that directly relate to their new powers and the sort of worshippers they'll earn, among mortals and monsters alike.

Authors note: This article, like every other article on this wiki, is a living article. It is constantly updated with new information and contains spoilers.

Basic Information

Anatomy

Every single demon lord is a unique being. There are no true limits to the forms demon lords can take, but some famous demon lords such as Morthos had surprisingly human appearances. Others though, such as Apep, a demon lord of fire, snakes, and the desert, had monstrous forms. In Apep's case he manifested as a truly gigantic burning snake the size of a skyscraper.

Biological Traits

Demon lords each have unique true forms that vary from one nightmarish princeling to the next. Even demon lords who lack true forms, such as Althos, have a unique form that they can take on. In Althos's case, it is the ability to transform into a black hole the size of an entire, somewhat large, galaxy. He can use this power to wipe out all life in an area at will, but has not yet manifested this enormously powerful anti-life ability.

Genetics and Reproduction

Demon lords, unlike some higher beings, did not produce higher-being children unless they were mating with a deity. If two demon lords mated they would have children who were either some type of greater member of a lesser species of demon or they produced pride-demon children who quickly grew to adulthood over the course of a few days.
If demon lords mate with beings who aren't demons or higher beings the sort of children they'll have depend on the mate in question. The most common constant in those cases is that those children will be half-demon, and will be tremendously powerful members of their kind. Some demon lords had thousands of children, and others had none. Demon lords of vermin or of other kinds of animals tended to be more fertile and thus reproduce more often than other kinds of demon lords.

Growth Rate & Stages

With one known exception every demon lord began its life as a demon. The majority of demon lords began their lives as demons who had once been mortals and then died, with their souls ending up in the Heart of Darkness and undergoing demonification over a few years to a few centuries. Some demon lords on the other hand were born as demons, the children of other demon lords or even other regular demons who can reproduce such as succubi and incubi. 
Inevitably demons who become demon lords reach a critical mass of power. The most common visual representation of this is when a demon becomes a pride demon, the tier of demon below a demon-lord. At this point, the demon in question almost invariably seeks to conquer a layer of the Heart of Darkness, and if they succeed in doing so they become demon lords. That said, it's possible for a demon to never be a pride demon and still reach the critical mass of power needed to become filled with a desire to lord over a layer. 
Demon lords also grow in power in a manner similar to both gods and archfey. As a demon lord gains more worshipers they increase in power, like gods, and as they gain control over more layers of the Heart of Darkness they grow in power like how an archfey's court increases its power.

Ecology and Habitats

The Heart of Darkness has 1,001 layers and it can still expand in size through the proper usage of sufficiently powerful magic. It has all manner of ecologies and habitats, from dense jungles to deep oceans, to layers with conditions that resemble those found in deep space. Some demon lords, such as Althos, prefer more extreme environments such as a forest shroud in eternal darkness, or a layer that is a vast sea. Some demon lords, such as Morthos, prefer tamer environments such as a gentle grassland where he could build a vast city filled with scholars who specialize in non-violent evil.

Dietary Needs and Habits

Demon lords didn't need to eat but many chose to do so. This is especially true among demon lords of gluttony, who often hungered for various things, usually things that are significant, in some way, to them. Some demon lords, even those who don't need to eat, captured and used humanoids and other sapient beings as sorts of livestock, keeping them in human-sized farms and using them as a human farmer might use a cow, or a chicken.

Biological Cycle

Demon lords are immortal, eternal beings. They can be killed, but they do not otherwise die. As time passes many demon lords spread their cults on the mortal dimension and grow in power and wisdom. That said, being a chaotic species not all demon lords behave the same way and indeed some demon lords exhibit extremely unusual reactions to the passage of time.
It was not unknown for demon lords to hide in their layers and become overtaken by paranoia or such brutal insanity that even by demon standards they become considered insane. Some such demon lords hid away in the deepest, darkest corners of their layers, while others went berserk and began hunting down the inhabitants of their layers, murdering anyone they came across. Such demon lords were not spared the universal end result of the end of the mythic age.
Some even stranger demon lords hid in their layers and began making prisoners of their layer's inhabitants. They didn't eat such creatures but instead used them for breeding stock. One example of this was the vermin & spider demon-lord Verduna, whose former layer of the Heart of Darkness is a vast cave system teeming with various sorts of spiders. Her children include driders, jorogumos, and even half-incubi vermin.

Additional Information

Social Structure

Demon lords stand atop social structures, or alternatively, they annihilate them. Many demon lords are surprisingly social entities who can be interacted with peacefully, for a time. They are consummate schemers and corruptors. 
On the other hand, some demon lords despise social structures and are more purely destructive entities who seek to kill and destroy all things. These demon lords tend to have followers who are both nihilistic and xenocidal, and thus are popular among demons but less so among non-demons. 
A rare few demon lords create vast social structures and seek something odd: they seek the expansion of the Heart of Darkness and the proliferation of demon-kind. They order their followers to do everything possible to boost the numbers of demons and their ilk in the multiverse, and to expand the strange, nightmarish homes of demonkind. Agustino would likely have become this sort of demon lord, had he successfully dragged Torus into the Heart of Darkness and become a demon lord.

Uses, Products & Exploitation

Demon lords are the kings, queens, and generals of the chaotic hordes of the Heart of Darkness. They are naturally capable of communing with the mysterious dimension itself and are the greatest of its servants. 
In the distant past, ancient gods of incredible power could also make use of demon lords such as through threatening them or even directly commanding them. Demon lords were also sometimes slain by gods in the name of defending their worshipers but sometimes ulterior motives were actually the primary motives. The Heart of Darkness hid and hides a number of valuable resources for exploitation by gods and their worshipers, including but certainly not limited to the Multiversal Abyss.

Geographic Origin and Distribution

Throughout the Heart of Darkness, though an extremely small handful of demon lords were able to manifest on the mortal dimension without difficulty and preferred spreading chaos and evil directly.

Average Intelligence

Varies wildly from demon lord to demon lord, but most demon lords were infinitely more intelligent than even high-elven sages. The most intelligent demon lords were as wise as gods of knowledge, and the least intelligent were less bright than the least intelligent animals.

Perception and Sensory Capabilities

Though individual exceptions existed, as a general rule most demon lords possessed all five senses and then some. As far as extrasensory perception went demon lords had total knowledge over all things going on in their layers and could change the features of their layers with but a thought (though some demon lords were better or worse at this than others). 
And of course, as befits their chaotic nature every demon lord varied significantly in personal power. Some demon lords were capable of challenging minor gods, and others ruled their layers through their wit and planning alone and could have been defeated by an adequately equipped team of mortals on a suicide mission.

Symbiotic and Parasitic organisms

Demon lords were masters of chaos. As such they could use the power of the Heart of Darkness to dominate other demons in the form of empowering them enough to allow them to evolve into greater demons, or in much rarer cases exert control over them by threatening them with the threat of devolution. Demon lords also inspired awe and reverence in demons, especially weaker ones, and could thus sway such creatures into their service through raw force of will.

Scientific Name

domini abyssum irent

Lifespan

Varies too radically to say. The shortest lived demon lord only lived minutes, and the longest lived demon lord was among the first demon lords to ever exist, and survived until the end of the mythic age.

Conservation Status

In the ancient past, there used to be less than one thousand and one demon lords at any one point in time. This is due to the fact that though explorers often claimed that the Heart of Darkness was infinite, it was not. It has one thousand and one layers, and thus even if every single layer of the Heart of Darkness had a unique lord, which had never been the case throughout the history of the multiverse, there would only ever be 1,001 demon lords.
As of the age of Althos, there is one demon lord. That said he fully plans to change that.

Average Height

Varies too radically to say. The smallest demon lord was less than 140 centimeters tall (around 4'6"-4'7") and the largest demon lord was the size of a small kingdom.

Average Physique

Varies too wildly to say.

Geographic Distribution

• Heart of Darkness