Sadly I do not know of many books with nonbinary characters. Freak Boy by Kristin Clark has a character that is non-binary/genderqueer/unlabeled, but otherwise there isn’t much in the YA field. I really liked Golden Boy by Abigail Tarttelin but the intersex main character in that story is only starting to think of himself as maybe-sorta-kinda-not-entirely-binary, so it lacks that particular focus on non-binary life that Pantomime does so well.
Sometimes people will read Mystique from X-Men as non-binary though it tends to depend on the particular writer for the particular story as to how well that is handled. I personally love Xavin from Runaways, and whole heartedly recommend the entire Brian K. Vaughan + Joss Whedon run on that series (stop before Terry Moore though).
Hey there! I’ve got a few.
Brooklyn, Burning by Steve Brezenoff is my FAVORITE nonbinary book of all time. The characters’ genders are never actually revealed, so it’s not, like, explicitly nonbinary, and you could just look at it as a test of your conceptions of gender roles (many reviewers do). But for me it was pretty obvious both of the MC’s were non-binary or trans. I mean, the dad says to the protagonist at one point: “I’ve got the only kid I know who doesn’t know whether to be straight or gay or a girl or a boy or what” which kind sends my non-binary bells ringing.
Everyday by David Levithan is alright, but I found that I couldn’t connect to the character’s nonbinariness since it was something that was forced upon them that they didn’t really like. So…maybe try it out, but I don’t think it’s as big of a winner for non-binary rep as most people seem to.
Love in the Time of Global Warming by Francesca Lia Block— now, in this book, the character is obviously a trans guy, but it’s also never really defined. Which allowed for me to be able to read a bit of nonbinary-ness into his character.
Also, you might want to check out Steve Brezenoff’s other book, Guy in Real Life. I’m only like a quarter of the way through it, and none of the characters are non-binary, but it explores gender in a really interesting and respectful way. There may be some potentially triggering stuff though…while the author is respectful, many of the characters (including one of the main ones) really aren’t.
Other than that, I unfortunately don’t know any others. And I have to say, that list from nonbinary.org, from the ones that I have read, is not very accurate. Or at least, it makes me question what they see as “non-binary.” But maybe some of the other ones that I haven’t read are better? Idk. There is a nonbinary/androgynous character in Sandman, but they don’t have a very big role. So maybe check that out if you’re into comics— Sandman is also just like the greatest, so.
Anyways, I hope that helped! If you try any of these recs out, let me know what you think!