Taxonomy of the Supernatural

Introduction

Initiates spent a lot of time attempting to note down all the things that go bump in the dark. This isn't an easy task. Many of such things would gladly take a bite from the people trying to observe them. There are hundreds of bestiaries out there, most correct in one entry while incorrect in another. However, certain things are common. The chief among them is the general taxonomy.
There are several major categories of supernatural entities, each of them requiring a different approach. Be advised - any instruction on how to deal with category A or category B creatures will be a general assumption. Every 'species' of supernatural entities out there should be treated as something unique. Yes. There are spells, enchantments and glyphs tailored to have an edge against one particular category of creatures. However, even that often has an exception or two.
Every category is further divided. This will be expanded upon in a description of the general categories beneath.

Categories

Cryptids

Cryptids are best describes as 'supernatural animals'. They typically aren't more malicious than a normal animal - they'll attack when hungry or threatened, and some might develop a taste for human meant, but in general they will not target human explicitly. Especially as you can except the Censor to make it slightly harder for them to perceive humans, making them TYPICALLY ignore them.
They also lack ability for tactics aside from pack predators and will typically strike when their nest is threatened or if they see you as an easy prey. Attacking a strong prey is typically a bad idea, as it means a risk of injuries. They also lack a guiding intellect behind them, as they are typically less interesting for the aberrants and an almost complete non-entities for Powers (they can be influenced by them, but aren't particularly interesting to them).
There are divided between Vagrants and Locals, depending on whether they are of local origin or not. Local might, for example, include a small regional subspecies of wolves that's capable of breathing fire or even having their fur be covered in fire (that doesn't make anything catch fire unless they want it to). Vagrants, in the meantime, come from Elsewheres, making then typically much more alien in nature.
Locals are typically further divided into animals and plants, while Vagrants are sometimes much more unique, to the point where trying to sort them out accordingly to such categories is largely considered a fool's errand.

Undead

Undead are, in short, humans that at some point were alive. But no longer are, and yet they are still capable of influencing the world. It is unknown why only humans can turn into the true undead. Animals can at best be reanimated temporarily using certain magicks, but only humans can achieve (relative) stability and self-sustainability in undeath.
Oddly enough, undead does not appear to be born through the power of any active Power in particular. It is something that baffles most scholars. They are instead born 'naturally' (although some claim that their Power is simply no longer active). Due to overbearing emotions, rituals or pure chance. They typically aren't counted among the most dangerous or numerous threats out there, but their human memories (and inhuman nature) often makes them quite threatening. They are also rather light on sanity and corporeal stability to those who face them.
Undead are divided between Corporeals and Incorporeals. The former are undead possessing physical bodies - think zombies. Their attacks tend to be physical as well, but there are exceptions - especially in the case of undead Initiates. The latter no longer exists as to material entities - think ghosts. Here the attacks tend to be mental or magical, except for poltergeist-like entities.
Corporeals are typically further divided between Sapients and Non-Sapients. The former are capable of making conscious decisions and controlling their bodies. Some might not even be aware of the fact that they are dead. This means that there are cases of them 'coexisting' with normal humans or Initiates. The latter are more animal-like, although some might be capable of vocalizations and holding 'scripted' conversations.
Incorporeals are divided between Bound, Unbound and Informatics. The first category is ghosts anchored to objects or people. In short, possessors or haunters. Unbound are capable of free movement, and Informatics are a relatively rare category of ghosts infesting the Internet. Which makes them fundamentally different from the 'normal' ghosts.

Aberrant

Aberrants are supernatural entities that were never humans. They are either spawned naturally in certain circumstances or somehow (scholars' are split) born through the will of the Powers. As a result, you can typically expect every aberrant to have some default overlord. Most remain bound to their patron's domains, which renders them incapable of exercising anything resembling free will. Others, in the meantime, can make decisions on their own. Or, in rare cases, betray their maker.
The perceived malevolence/benevolence of aberrants depends almost entirely on their patron Power. They are also the most eldritch of all supernaturals. Their nature makes them particularly heavy on the sanity and corporeal stability of those interacting with them. Most can spare humans by appearing in a form that they are slightly less uncomfortable with. Most, however, doesn't care about humans enough to bother.
Most of the aberrants appear to reside in Elsewheres. Some cross over willingly for a variety of reasons. Others are summoned through certain rituals and magical spells. Quite often the summoners discover that they are no longer capable of sending them back. Making them discover that there are things worse than death. And letting the summoned aberrant roam free. Until it grows bored or some Initiates manage to corner it.
Lesser Aberrants are divided between sapient non-sapient Servitors and sapient Servants. Once again it has to be said that lacking sapience doesn't mean lack of vocalizations and lack of ability for independent decision-making. The difference is that Servitors are incapable of disobeying their patrons and their intellects are used purely to execute their mission/goal of existence. Servants are at least technically capable of going wayward.
Greater Aberrants are technically a part of the aberrants, however due to their fundamentally different nature, they are counted as being that are fundamentally closer to gods rather than 'mere' supernatural threats. They are, after all, an individually unique entities rather than species.

Demihumans

Demihumans are former humans that have stopped being humans without dying (regionally referred to as the Fallen, the Lost or exhumans). This is the fate that typically befell the Initiates that have overdosed on certain magic, gathered too much Attention of some Power... and lost their humanity.
They are a varied bunch. In many cases capable of further reproduction. As a result, they are best imagined as non-human sapient species. Some of them live on the outskirts of civilization, others have found their niche among the humans. The majority live in very small groups (family-sized) or as singular existences. They relatively 'human-likeness' in behaviour tends to evaporated the further you get from the first generation (the one that at least theoretically remembers being human).
Every species of the demihumans is dedicated to a single Power. However, they are all sapient by default. This means that they are capable of not following their Patron, even if they can't use any other magic than theirs (it's not uncommon for cultists to 'fall' into demihumans and be suddenly cleared of perception-warping Attention level, leading to them ceasing connection to their cult).
They are also much more resistant - or entirely invulnerable - to sanity damage and incorporeal instability. Instead, the creatures and items causing those influence them negatively in different ways. The primary one is feeling of oppression and dread (replacing sanity damage) and physical harm or sickness (replacing stability damage). They also tend to find themselves unable of using magic not connected to their patron, but this varies.
Fallen are extremely unlikely to 'unfall' themselves. There are tales of the Fallen achieving that, but typically the price is rather steep. There are divided internally according to the Pantheon to whom their patron belongs.
Nightmares are a rare cases of particularly powerful and gifted demihumans, reaching a level that makes them equal magisters, heresiarchs etc. in combat. Those appear to be random, perhaps being a sign of the Power behind them being more interested in the human in question, leading to a better 'quality' of a demihuman in question. However there are also cases of demihumans developing themselves into a Nightmare level later on. No one knows what decides that.