Therians:
Forums.Therian-Guide -- Founded in 2002 and still present and somewhat active it seems. I think this was one of the two largest therian boards of the early 2000s. This was the "scientific/respectable" one that always took a hard line on the possibility of physically shapeshifting. There was a smaller, rival board I can't find again that was where all the jilted outcasts went (edgy 14 year olds) who argued you could
totally shapeshift and was crawling with teenagers pretending to be wise werewolf shamans who would mentor you... if you were worthy. Just scrolling through that P-shifting stickied thread on FTG and it's like a time capsule -- you can see the mix of shitty low-rez nature photos (ahh, dialup), cheesy art, and then a few furry avatars sneaking in. Incidentally, the demon-dragon-wolf thing was already around, they called themselves polyshifters, and most therian boards thought they were posers. They usually got pushed to the boards that were fringe even to this subculture, or the Otherkin sphere. The flame wars that would erupt when a demondragonwolf would pop up were
glorious.
School of Shifting -- This is on weebly now, but I'm pretty sure I recognize this site from earlier. I think it used to be on Angelfire originally (for whatever reason, probably the name of the host, most English-language small 90s magic/occult or occult-adjacent subculture sites were on Angelfire. It was a meme in those circles.). Shapeshifting was basically 75% of the discussion on any therian board, along with all the signs that proved any given angsty teen was definitely actually a wolf inside and that's why they didn't fit in. (Sound familiar?)
There were a few other therian boards, but the population at the time was a lot smaller than the vampire subculture it seemed, and it was likely because even in the magic/paranormal-friendly corners of Web 1.0, claiming you had a nonhuman soul was one of those things that was "lol, come on", while claiming magic/magic with the name changed was "seems plausible, go on". Funny how it's the opposite now.
Vampyres/Vampires (yes, there were as many endless autistic fights over how to spell it to indicate the subculture as you think there were):
Sanguinarius -- This is the big one, the great-grandaddy of post-Usenet vampire sites and the central hub for all things psy and sanguinarian vampyre (that wasn't the bloodplay fetish community -- those guys were officially unwelcome, but it was an open secret there was an overlap). Established in 1997 and was still getting updated until 2014. Won't load past the landing page on Waterfox, but Edge worked. Look for posts about a jackass named "Father Todd" to see a shining example of the grooming sex predator that's rampant in troon circles nowadays. Forum is unfortunately unreadable without an account.
Father Todd was the sanguinarian vampire founder and head fangsmith of Sabretooth Fangs, a prosthetic teeth and contact lens company that did work for a few Hollywood movies of the era even (fangs were meh IMO, Dnash's were better, but their contact lenses were incredible). He was periodically in legal trouble, unsurprisingly. I never met that guy, but I did get a set of fangs made by his rival, Dnash, who was a based, very fun dude (who did not claim to be a vampyre, but loved making costume teeth and was an amazing craftsman, his shit was A-tier Hollywood grade that would run you $300 for a full set like the logo in his business card below (worth every penny). Day job was a dental technician. Side gigs were his metal band and his fangsmithing). He always signed his business cards by biting them. Somehow, I still have an (unsigned) card kicking around. It's shiny like chrome, camera can't catch it unfortunately. Enjoy a relic from late 90s/early 2000s vampyre culture.
Drink Deeply And Dream -- This was one of the other big vampyre hubs, also launched in 1997. Population here skewed mid-late teens, while Sanguinarius was more 18+. Forum sadly picked up a requirement to register to read it, and I doubt anyone is still handling signups. A shame, because it was huge and would be a fantastic time capsule. A lot of these early subculture boards went fully private somewhere after 2005.
Psi-Vamp -- A Tripod-hosted survivor from 1999! Different from the two above as it's a personal site dedicated solely to life as a psychic (psi/psy) vampire. No blood drinking. Psy and sang vampirism were the two big "species" of vampires back in the old subculture, with of course some snowflakes claiming to feed either way because even in a blizzard, someone's got to be the biggest snowflake.
"
Vampires Today" -- Not a forum, but a short book written by Joe Laycock documenting the vampire subculture of this era (ignore the cringy cover, it was the publisher's choice). Interviews a bunch of the better-known members, especially around the US Southeast. It's accurate.
Otherkin:
Embracing Mystery -- Otherkin were rare as hell on the internet before 2005, at least from what I saw (maybe they were all hiding on IRC or ICQ chatrooms, or AOL-hosted boards or Usenet). Most peoples' quests for specialness were able to be satisfied with being a vampire, a therian, or practicing some form of magic. (And the stories I could tell about those late 90s magic/occult sites! Now
there is a subculture that's been utterly consumed by Woke, even the Chaos magicians. The old chaotes from the 80s and 90s would've bitchslapped all the little neo-Puritans who don't even know how to design a proper sigil. They're literally the shit all that was culture-jamming against.) This was the only active forum of any notable size I ever found for these guys. Site is in tatters, but the main page and some of the articles survive. The current forum isn't the original EZboard one from its heyday, and the archives of that are inaccessible due to a stupid legal dispute over rights to ezboard archive content (not just for this site, for all ezboard stuff). I may have seen the Patient Zeros for both the demon-dragon-wolf
and the angel-demon-god-kin on this board in the early 2000s (that last guy was a cow even to that board's users). Sheer entertainment, my favorite private cattle pasture. Also met one of the only oldschool, theistic Satanists I ever ran across on this board. Pleasant German gentleman, knew his Goetia and medieval necromantic texts. I have no idea what he was doing on that board even briefly, because he was way too knowledgeable and serious for that circus. Maybe he, too, was farming some milk.