Otherkin are people who identify in some way as non-human. Broadly defined, while otherkin are human in outward form, they believe themselves to be in spirit what are generally considered to be mythological or legendary creatures. Some may claim to be able to shift mentally - meaning that they may experience the sense of being in their particular form while not actually changing physically. The existence of Otherkin is variably explained as being made possible through reincarnation, having a nonhuman soul, ancestry, or symbolic metaphor.
Common creatures otherkin identify as include angels, demons, dragons, elves, extra-terrestrials, fairies, kitsune, lycanthropes (werewolves), and vampires.
Otherkin Internet Communities
The oldest Internet resource for otherkin is the Elfinkind Digest; a mailing list started in 1990 by a student at the University of Kentucky for "elves and interested observers". Also in the early 1990s, newsgroups such as alt.horror.werewolves and alt.fan.dragons on Usenet, which were initially created for fans of these creatures in the context of fantasy and horror literature and films, also developed followings which identified as mythological beings.
On 6 February 1995, a document titled the "Elven Nation Manifesto" was posted to Usenet, including the groups alt.pagan and alt.magick. On Usenet itself, the document was universally panned and considered to be either a troll or an attempt to frame an innocent party. However, enough people contacted the original author of the Elven Nation post in good faith for a mailing list to spin off from it.
The modern otherkin subculture grew out of these elven online communities of the early-to-mid-1990s, with the earliest recorded use of the term otherkin appearing in July of 1990 and the variant otherkind being reported as early as April 1990. The therian, vampire, and draconic subcultures are related to the otherkin community somewhat, and are considered part of it by most otherkin, but are culturally distinct movements of their own despite some overlap in membership.
I think that goes way back before the 90s. Those sorts were leaving “Frodo lives” scrawled everywhere in the late 60s.