While "a theri is a theri is a theri" for many of the legal and social issues surrounding TheChanges, not all therianthropes are created equal. Their various forms, capabilities and interactions with unchanged humans lead to very different life experiences for different theris.

Within TTU, attempts at classification generally lead scholars to identify between 4 and 9 subgroups of therianthrope, out of the 10 listed here. While these divisions typically carry no legal weight, and while their edges are considerably blurry, such clusterings do provide a starting point for science (both hard and social), and are generally backed up by the common characteristics that group members share.

The numbers given along with "Percentage of Theri Population" are rough estimates designed to give some sense of each subgroup's visibility in the population at large; their wide range is meant to take into account the slow spread of therianthropy over time. In later eras, populations will trend toward the higher end of the range.

The total (nonhuman) therianthrope population is between 0.01% (1/10,000) and 0.1% (1/1,000) of humanity, increasing over time.

A TTU "were" has a theri form of an animal that existed pre-Changes. A "classical" werewolf -- the person shifts between a human form and a four-legged wolf form -- is a "were."

Werewolves are the most common -- it's typical to correlate this with the fame of the myth -- but other examples range from big cats to various mammals, birds, snakes, and sea animals. (Most weres' animal form is predatory; though this could simply be a reflection of the human bias toward charismatic megafauna.) There's also a strong Eastern tradition of this sort of therianthropy -- variously called obake, bakemono, yokai, or hengeyokai -- among which foxes (kitsune) are popular.

Physical characteristics: When in theri form, weres are to all surface appearances normal animals. Some are unusually large for a representative of their species, but size will be within the limits of the species' possibility. They retain their human memories and intelligence, and usually their full consciousness and volition. A very few have the capability for human speech, but typically communication is accomplished through magical effect, nonverbal means, or through shifting back to human form.

Approx. % of theri population: 30% (10K-100K in the USA).

Relative difficulty of first shift: Moderate. Though their new form is rather different from their human one, there are plenty of examples of it around for would-be theris to study and attune themselves to.

Shift back and forth at will?: Yes; returning to human form is an innate ability for weres. (Though a very few claim they can only change to animal form under a full moon, or otherwise do not have control over their shifts.)

Predisposition to use magic: Moderate; roughly 25-30% of weres are also active mages.

Socialization pre-Changes: Largely online on alt.horror.werewolves ("AHWW") and as a minor subgroup at furry conventions. People who considered themselves animal spirits in human bodies were the ones who first coined "therianthrope" (or "therian") as a self-label -- though pre-Changes the term generally referred only to what are now called weres (and they generally considered those with more fantastical nonhuman selves to be posers).

An "anthro" has a theri form that is a human/animal hybrid. Anthros' forms are basically human in shape and capability, but have features of animals (or mythic creatures). A "Hollywood" werewolf, where a man changes into a seven-foot-tall, two-legged furred beast, counts as an "anthro."

Anthrowolves are the most common creature type by a small margin -- it's typical to correlate this with the fame of the werewolf myth -- but there is an enormous spectrum of anthros in mammal, reptile, avian, and even aquatic and insect styles (with mammals being the most common). A majority of anthros have features from a single source animal, but hybrids (e.g. fox-cat, tiger-wolf, zebra-unicorn) are reasonably common. Superhybrids (mix-and-match features from 3+ species) are also known, but sufficiently strange forms may be lumped in with Mythics (see below).

Physical characteristics: All anthros stand upright; have the capability for human speech; have two legs (which may be plantigrade or digitigrade or hooved); and have (at least) two hands with opposable thumbs. The face features a elongated muzzle, beak, etc., appropriate to the nonhuman aspect of their form, and is the most recognizably nonhuman part of their anatomy. Almost all are 5-8 feet tall (1.6-2.6m). A few have wings or extra arms, but most are four-limbed. Most have tails. The body is generally covered with fur/scales/feathers/etc appropriate to the nonhuman aspects of their form, but typically has human secondary sexual characteristics (e.g. humanlike genitalia, and chest-mounted mammalian breasts in females).

Approx. % of theri population: 50% (15K-175K in the USA).

Relative difficulty of first shift: Easy. The similarity of anthro bodies to their prior human ones means that anthros find it relatively accessible to attune themselves to their new form. (Though of course therianthropy in general is still very difficult.)

Shift back and forth at will?: Maybe. A number of anthros, since their bodies still offer the advantages of opposable thumbs and human size, are happy to completely abandon their old body. Studies of anthros in which they were asked if they could shift back to human form generally split down the middle: 50% yes/20% no/30% unwilling to try (or don't know). Most of these shifts are via memory resonance.

Predisposition to use magic: Minor; perhaps as many as 15% of anthros are also active mages.

Socialization pre-Changes: Online on alt.lifestyle.furry ("ALF") or other newsgroups of interest - and a small but well-known contingent at furry conventions. Pre-Changes, self-described as furry "lifestylers" -- those who worked their online identity, or "fursona," into their lifestyle rather than treating it as a fiction for socialization purposes. (If you're unfamiliar with furry fandom and its vocabulary, examine WikiFur. Also note that furry fandom exists in TTU, and even got a modest boost in popularity due to TheChanges -- but the terminology has changed due to popular corruption of the term "furry", and most people that our Earth would describe as "furries" call themselves "furfans" or "furfen" in TTU.)

A mythic is any non-anthro, non-were theri. It is a catchall category rather than a grouping of common features: any theri form that doesn't fit a more specific classification is lumped in with "mythic." Most commonly, this refers to creatures with a well-known existing archetype in popular mythology. (Some scholars try to limit the "mythic" category to those theris, and throw the remaining outliers into a different catch-all category, but this merely shifts the problem.)

If there is a "most common" among mythics, it would be the ones whose backgrounds are (metaphorically and literally) larger-than-life-sized: dragons, gryphons and unicorns. Centaurs (and other, stranger "-taurs" of various kinds), pegasi, ki-rin, and other big-name myths are reasonably well-represented. The remainder is a mixed bag and can get outright bizarre. Note that there are several classes of mythological creature that nevertheless fall under one of the other theri categories: for instance, werewolves are weres; kitsune are polyweres/weres; mermaids and minotaurs are quasihumans/anthros.

Physical characteristics: Variable, to almost ridiculous extremes. Most are capable of human speech. The form may conform to standard mythological roots, or come from some intensely personal mythology that leaves little to hang an expectation on. Sizes may range from 1 foot (.3m) long, up to approx. 60 feet (18m) nose-to-tailtip for the largest dragons. Bodies may have inherently magical (or otherwise physically impossible) capabilities, such as dragons' flight and firebreathing; this makes it awfully difficult to define whether a mythic who can't consciously cast spells is a mage or not.

Approx. % of theri population: 10% (3K-35K in the USA).

Relative difficulty of first shift: Difficult to extreme. Since theris-to-be must attune with a genuinely foreign body, with very little reliable reference material to aid the mental alignment, mythics must be even more firmly committed to their new lifestyle than usual, and have given the details of their identity some serious introspection. In the later eras of TTU this does get easier, as new mythics can follow in the footsteps of the existing ones.

Shift back and forth at will?: Yes, sort of. The extra difficulty inherent in an odd-shaped (and often large) form means that mythics have a really compelling reason to spend time in human bodies. However, they don't generally get weres' benefit of having shapeshifting-at-will be an innate part of their mythology. Perhaps 75% consider themselves to have only one "natural" form (their mythic one), but use memory resonance or shapeshifting magic to return to their old human shape as needed. (For some, this is the only actual magic that they know. Also n.b. the preponderance of magical shifts is one of the factors feeding the notion that all mythics are mages.) Another 15% can apparently shift as an innate effect, whether the mythology for their creature type historically mentions shapeshifting or not. An unfortunate 10% are stuck in their new form and get to deal with living in a world not designed for their bodies.

Predisposition to use magic: Extreme. It's popularly assumed that all mythics are mages; this isn't true, but easily half of mythics actively cast spells of some sort (many estimates are upwards of 75%; some that count theris with inherently-magical forms as mages go even higher). Some therianthropy scholars suggest that the personality and interests necessary to change into a mythic in the first place have a strong overlap with magical aptitude.

Socialization pre-Changes: Online on alt.fan.dragons ("AFD"), alt.mythology.mythic-animals ("AMMA"), the Gryphon's Guild (Web-based), or one of several mailing lists (largely under elven supervision). Often self-described as "Otherkin" (a term first popularized in elven circles), though "theri" is not unknown (and others simply label themselves by their creature type). A miniscule but close-knit subgroup at furry conventions.

A quasihuman is a theri whose form is mostly human with visible nonhuman elements. Largely, quasihumans' forms come from myths depicting changed-human or near-human figures; this category covers vampires, angels, some devils (such as succubi), mermaids, minotaurs, and the like. It also covers humanoid beings with no bestial characteristics -- mostly elves, though a few other Tolkienesque and/or fantastic races are known to exist in very tiny numbers.

This is a relatively small group, and elves are by far the most common, if only due to their greater organization before The Changes and higher profile afterward (aided in no small part by CharacterElf). For all their popularity in myth, vampires are notably absent immediately after The Changes, and remain difficult to find for quite some time; VampiresInTTU has more detail.

Physical characteristics: In most cases, the theri's new form will be identical to their old one, with the physical additions of their new form: added fangs or feathered wings or legs transformed into a tail or whatnot. Elves tend to be tall and frail, though there's a substantial contingent of short/child-sized elves (Elfquest Wolfrider style). Notably, quasihumans' shapeshifting effect often seems to power itself through the body's stored energy if the original form was overweight, leading mages to jokingly refer to the "10-minute elf weight-loss program."

Subgroup Of: Anthros and/or mythics.

Approx. % of theri population: 4% (1.5K-15K in the USA).

Relative difficulty of first shift: Surprisingly difficult. Since the new form is in most respects identical to the old one, the theri-to-be must have an unusually strong sense of self to separate their human resonance and their theri resonance.

Shift back and forth at will?: Due to the resonance issues mentioned above, most of these changes are permanent; elves in particular often shift once and stick. Mermaids and angels are notable exceptions; most angels can manifest or hide their wings at will, and mermaids usually regrow legs when out of the water.

Predisposition to use magic: High. Vampires are nearly universally mages (see VampiresInTTU). Elves seem to have a natural affinity, with maybe 50% of them being active mages. The others bring the average down some.

Socialization pre-Changes: Elves largely gathered on several elven-run Otherkin mailing lists. Those with a lot of interest in vampires generally circulated in goth crowds -- although these were not necessarily the same people who ultimately changed! Most other quasihumans hung out with different types of theris, if they were able to socialize with theris at all.

A dinosaur is a type of were whose form is that of ... well, a dinosaur. They are mentioned separately from weres because, while dinosaurs clearly existed on Earth before the Changes, the fact that dinosaurs were extinct did create additional challenges for would-be theris. Most weres were able to meet, or at least watch on TV, the animals with which they identified; dinos had to make do with bones, imagination and artwork, in a similar way to anthros and mythics. Dino theris also quickly became sought after by paleontologists for research purposes, although the debate over whether any dino theris actually match the fossil record is fierce and ongoing.

Raptors are the most common dino theri. The largest dinos, including T. Rex, are unknown as theris despite their pre-Changes public appeal; some theri scholars assert that this is evidence for a size cap of some kind on would-be shapeshifters.

Physical characteristics: As per their dinosaur type -- although factors not directly confirmed from fossils vary widely! Some raptors are feathered, some scaled; dino theris seem split between cold- and warm-blooded; coloration and behavior are all over the map. As with weres, dinos retain their human intelligence and volition while in dino form, although many lack the capability for human speech.

Subgroup Of: Weres

Approx. % of theri population: 2% (500-6K in the USA).

Relative difficulty of first shift: Moderate to difficult.

Shift back and forth at will?: Largely. Many dinos seem to shift through the same innate mechanism that weres use.

Predisposition to use magic: Moderate, as with weres.

Socialization pre-Changes: Mostly found each other as a small subgroup of furry and/or dragon circles.

A polywere is a theri with multiple related nonhuman forms. Generally a polywere's shifting capabilities will be: human, human/animal hybrid (i.e., anthro), and animal (i.e., were), of the same animal type; such theris are also called "anthroweres." Other configurations are possible, such as mythics that also have a hybrid/anthro form, or theris whose archetype has two related forms it can shift between (examples include some anthros whose form can be two different genders, or who transform into a combat-oriented form for self-defense).

Anthroweres are the majority of this group, led by anthrowerewolves; beyond that, it's a mixed bag with a lot of individualism.

Physical characteristics: Anthroweres' forms tend to have the characteristics of the anthro and were forms as described above. Polyweres that have at least one anthro form (which is nearly all of them) generally follow the anthro pattern for those forms.

Subgroup Of: Anthros and/or weres, with a side order of mythic.

Approx. % of theri population: 3% (1K-10K in the USA).

Relative difficulty of first shift: Extreme. Individually, the forms have the advantages of simplicity (anthro) and good reference availability (were), but taking on a single new form is hard enough, and gaining two more at once takes a rare breed -- and a specific conception of a creature with innate shifting power.

Shift back and forth at will?: Yes, by definition. Polyweres' shifts are innate. There are no known cases of polyweres who are physically unable to shift back to human form.

Predisposition to use magic: Surprisingly low among anthroweres (no better than in the population at large!); but high (up to 50%) among the more exotic members of this group. Theri researchers are at a loss to explain why so few anthroweres are mages; there's no logical reason why it should be that way.

True shapeshifters are the rare theris that have no fixed nonhuman form. Although anyone with access to sufficiently powerful magic can temporarily become any form they like, those changes require the continual expenditure of energy and willpower; shapeshifters can become anything as an innate effect and so can effortlessly take on any theri form for any length of time, retaining their new shape even if knocked unconscious or counterspelled. See ShapeshiftingInTTU for more detail.

Physical characteristics: Basically any living species (normal, theri or fantastic) that they desire -- with the caveat that shifters can't innately access human forms besides the one they started with. Theri researchers suggest that the leftover resonance of their pre-theri form is strong enough to disrupt such attempts. (N.b.: as a conscious, magical effect, it's still possible.)

Shifters also have to have a pretty clear idea of what they want to change into in order to get the resonance stable; when first using a new type of form, many will wait until a theri is physically present that they can mimic. (More experienced shifters have built up a repertoire of forms that they've previously used and can reactivate with minimal effort.) Most shifters will retain human speech regardless of their chosen form.

Relative difficulty of first shift: Beyond ridiculous. There's nothing to align your resonance to when trying to become a shapeshifter. Many of the earliest shifters describe the discovery of their powers as basically accidental, and by the time they found out that what they were doing was impossible, they were already doing it. Most shifters learned their powers under the guidance of an existing shifter, and even so, a large majority of would-be shifters just don't seem to "get it" -- there seems to be some other factor out of common reach.

Shift back and forth at will?: Yes. Very yes.

Predisposition to use magic: Most shifters don't use magic, whether or not they can; it has severe side effects. This, plus the small sample size, makes measuring "predisposition" hard. See ShapeshiftingInTTU for more.

Socialization pre-Changes: N/A; the first shifters mostly had no clue of what they would become. Those who believed themselves to be true shapeshifters pre-Changes, if they became theris at all, generally ended up settling into the form they most strongly identified with.

Inanimates are theris whose form is outside the animal kingdom: plants, living minerals, or stranger things. Who they are, and how they got that way, is outside of the boundaries of normal therianthropy -- but since their condition seems to follow similar rules, some classification systems include them.

To say that inanimates are rare would be an understatement; inanimates are to rare what rare is to common. The least rare of them would probably be the occasional plant theri, like a dryad or an ent.

Physical characteristics: Since the capabilities of non-animal bodies don't generally include niceties like movement, speech, etc., most of the capabilities of these theris' forms come from whatever magic they are able to still wield. Some theri researchers believe that, in a certain sense, these theris have become beings of elemental magic, with their spirit continually gathering and using energy to occupy a form it's not meant to fit into. This suggests that placing inanimates in an antimagic field for any non-trivial length of time would immediately kill them.

Subgroup Of: Mythics

Approx. % of theri population: <0.1% (5-250 in the USA).

Relative difficulty of first shift: N/A. People cannot simply will themselves into becoming something outside of the animal kingdom. These theris are always the product of long, dedicated magical experimentation, and/or severe magical mishap. (Most often both.)

Shift back and forth at will?: No. Once resonance has gone this wrong, it requires outside intervention to reset -- if it will reset at all.

Predisposition to use magic: Universal, though the causality goes the other way around: it's only mages who fool around with effects powerful and strange enough to cause this sort of transformation.

Socialization pre-Changes: N/A. Even post-Changes socialization is marginal -- generally via private communication once finding each other through some other venue.

It's linguistically inaccurate (and could be considered offensive) to apply the word "therianthrope" -- literally meaning "beast-man" -- to a human. However, in TTU, "therianthropy" is the accepted term for the broader phenomenon of physically shifting to match one's self-image, so virtually everyone uses that label for humans who have undergone a therianthropic shift into a different human form. (This is not without its controversy; see TransgenderInTTU.) Mages are also included for completeness here, even though their classification as theris was due to an early misunderstanding about the nature of therianthropy.

This section is under heavy revision. To contribute, please read and join the discussion at Baxil's LJ.

A number of people used the opportunity of TheChanges to alter themselves in ways that had nothing to do with species -- using a therianthropic shift to change their physical sexual characteristics to match their gender of identity.

In fact, even years after The Changes, a high proportion of trans theris try to live in ways that minimize others' knowledge of their change. There are many reasons for trans theris' relative secrecy -- not the least of which are quality of life and personal safety. Even in TTU, gender issues are somewhat taboo, and the idea of broken gender barriers can provoke a disproportionate visceral reaction.

Physical characteristics: Human. (Even those with atypical genital characteristics, such as dual genitals, are within the range of recorded human variance -- though functioning hermaphrodism does push the boundaries a bit. Conditions beyond that -- such as smooth skin where genitalia would normally go; or turning into a being with multiple, distinct human forms -- would lead to that individual being labeled quasihuman. Classification schemes that contain both this category and quasihumans tend to have a thin boundary between the two.)

Subgroup Of: N/A

Approx. population: Estimates of gender-trans therianthropic individuals range from 0.1% to 1.5% of the human population (up to 5 million within the U.S.) -- meaning that at minimum, there are as many gender-trans theris as all transspecies theris put together, and most likely they outnumber transspecies theris by 5:1 or more. But trans theris, for reasons given above, are vastly harder to count than their more visibly changed kin.

Relative difficulty of first shift: Easy. The changes needed for the new form are straightforward and there are enormous numbers of examples around to aid visualization. (Though of course therianthropy in general is still very difficult -- all of the usual rules in BecomingATheri apply.)

Shift back and forth at will?: Generally no. Although cases of memory resonance shifts are known to exist here, they seem to be disproportionately rare for gender theris. A popular theory that many gender theris find belittling is that this due to resonance overlap, since the memories are from the same species; transgender activists point out that gender theris are far more likely to change in isolation, less likely to have a community of fellow theris to compare notes with, and more likely to want to put their shift permanently behind them.

Predisposition to use magic: Unknown, due to poor data on the gender theri population. Samplings of known gender theris suggest a moderate to high predisposition (30% or more?), but it is broadly assumed that this number is high due to sample bias, since magic and magitech firms are significantly more accepting of nontraditional employees and there is a large concentration of "out" gender theris in those fields.

Socialization pre-Changes: A mixture of online and in-person groups. Online resources included alt.transgendered, alt.support.srs and soc.support.transgendered. A number of large cities had specifically TG organizations in the 1990s, such as San Francisco's ETVC (now TGSF) and the Saint Louis Gender Foundation. Note that in the mid- and late 1990s, support for TG individuals was spotty among LGBT organizations (for example, PFLAG did not officially include TG issues in their mission statement until 1998).

Using the word "therianthrope" to describe human mages is fundamentally inaccurate, for the same reasons listed above. However, the earliest attempts at theri classification included them. So did popular sentiment shortly after The Changes. Since magic and therianthropy sprung up side by side, and since they do demonstrably have some correlation, it was broadly assumed that mages were somehow different in the same way that theris were -- and a product of the same (albeit subtler) transformation.

It would take a few months to dispel these assumptions. Until early 1997, most theri classification systems listed mages as a subgroup of therianthropes. As time passed, it became more common to (properly) categorize magic as a skill accessible to anyone, and mages as merely people (of any form) who had learned that skill.

Ironically, as magic became more widespread and disciplined, mages would begin replicating the shapeshifting effect that theris were intuitively accessing -- which gave almost anyone the ability to temporarily spend time in another body, lowered the threshold of effort required for true therianthropy, and made theri classification an even more hopeless goal.

Approx. population: Depending on wording and methodology, surveys generally put active magic users at 1%-3% of humanity (up to 10 million within the U.S.) Include the number who have ever attempted any sort of spellcasting and achieved any level of demonstrable success, and the number climbs as high as 30%.