Ever have a sudden epiphany? Has this epiphany been that you weren't actually human?
If you're saying, "Why, yes! I have!" then I have an explanation for you. It won't stop me from backing slowly away from you, keeping my eyes on you the whole time, but at least now you can be reassured in the knowledge that you're not, unfortunately, alone.
People who think they aren't people call themselves "Otherkin." (Their friends and relatives usually call them "loonies," but that may be a tad harsh.) Given the kind of wackiness that's out there on the 'web, it will come as no surprise that there is a whole internet community of Otherkin (you can peruse the web pages, and/or join various listservs, here). The definition of an Otherkin is "a person who, either biologically or spiritually, claims kinship with another species." Now, we're not just talking about someone with a marked physical or personal similarity to an animal, such as saying that someone is as fierce as a tiger or as strong as an ox, or when my students immediately prior to major exams compare me to a cold-blooded poisonous snake. No, we are talking about people who think that they actually are members of another species, and it bears keeping in mind that here we are using the word "species" to include creatures which, technically speaking, don't exist, such as elves, naiads, centaurs, dragons, dryads, and so forth.
Perhaps at this point you are saying to yourselves, "what the hell?" or some stronger variant. To which I reply: just wait, I've hardly even started.
Otherkin claim that there are two main types; ones who have the spirits of another species (or elf, et al.), and ones who actually are honest-to-Legolas descended from one. The site states that the latter claim is "virtually unprovable except through extensive DNA testing," but cites as examples the descent of the ancient Irish kings from the Tuatha de Danann and the Japanese royal house from dragons. They say, without any sense of irony, that both of these have "some support from ancient texts," because of course it goes without saying that anything appearing in ancient texts has to be true.
On the website is a list of Otherkin, each entry submitted by someone who really believes that they are one. There are thousands of them. A few, just so you can get the flavor of it, are "Fangtastic" (a werewolf/vampire hybrid, presumably to obviate the need of deciding between Team Jacob and Team Edward), "Xandrael" (an angelic being who lives in Oswego, New York -- I've been to Oswego and you have to wonder why, if you were an angel, you wouldn't pick somewhere rather nicer), "Faelaenx" (a dragonish sort), "Nitefae" (someone who "thinks she is a sylph but is still exploring"), "Lynaelynx" (one of the big cats, not surprisingly; and must they all have an "x" and an "ae" in their name? Is it a club requirement?), and, finally "AmaltheaSkye" (a unicorn, who makes up for having no "x" or "ae" by having a superfluous "e" at the end).
Now, I realize that some of these people -- perhaps, in my optimistic moments, I can even believe that most of these people -- are merely having some fun with role-playing, participating in a kind of free-floating Dungeons and Dragons game without any rules. I've no problem with escapism, per se, but I myself can't escape the conclusion that some of these people have escaped permanently. Some of them claim peculiar aversions which are supposedly emblematic of your actual identity (e.g. if you're afraid of iron, you might actually be an elf; if you're afraid of running water, you might be one of the Sidhe; if you're afraid of Universal Health Care, you might be a Republican; and so on). One article gives some moral support to those who are in the process of "awakening" (read it, if you're curious, here), and seems to take the whole thing completely seriously.
I know I shouldn't poke fun, as it's not nice to laugh at people who hold beliefs that are, frankly, delusional; but given that that's my opinion about most superstitions, I suppose it's to be expected. And, honestly, as delusional beliefs go, thinking you're a dryad is pretty harmless -- I don't suppose it'd cause you to do anything worse than dressing in earth tones and trying to photosynthesize when you're hungry. I can see how thinking you're a wolf, tiger, vampire, or (god forbid) a horsefly, could lead to some unpleasantness at work or home, but otherwise, it doesn't seem to be in the same category as the delusions which make people blow themselves up in crowded marketplaces or think they have the right to march out and take over the world.
So, if you want to run about claiming that your real identity is Xaepnoo the WeaselFaerie, knock yourself out. Myself, I think I'll stick with Gordon the Plain Old Human. It may be pedestrian and dull of me, but there you are.