Nott from Critical Role, for no other reason than this. Since she is being played by a man, the other players accidentally call her "him" on occasion, as in referring to the player instead of the character, and I'm choosing to take that as in character meaning the others accidentally think of/call her as male.
Because I just read this whole thing - First, what I came here for - Axel/Lea from Kingdom Hearts is a transdude. Long before I ever identified as such or knew the correct language for it, he's just. Always been obviously AFAB to me??? And its still an eternal source of frustration that so few fix writers (exactly one to date!) share my assessment of the beautiful disaster that is this character. (Other KH trans headcanons - more commonly held that Marluxia is at least nb/genderqueer even if all it amounts to is gross jokes. I like Braig/Xigbar as a transdude as well, even if he's an asshole (they're all assholes to one degree or another, but him in particular lol) . I remember once I reactively made a full set of headcanons that EVERY SINGLE MEMBER OF THE ORIGNAL ORGXIII was trans and how/why. I think tiny me got mad at lack of rep and went off on one of my ILL MAKE A BETTER AU WITH BLACKJACK AND HOOKERS SO THERE. I've since learned to dial it back some ^^;;;; )
Not really a headcanon so much as something I find amusing to do: making Remilia the world's most dumb and baffled transgirl in all existence. We're talking Goku levels of dumb about these matters. Well. Not. Quite Goku levels of dumb, given that that boy had like no sense of personal space because Toriyama loves terrible jokes too much. BUT. Dumb as rocks.
this is more shitposting than actual headcanon, but okay, hear me out here adora is trans bc transformation sequence is obv a metaphor for transition glimmer is trans bc she likes being smol and cute but will still fite you to prove she can bow is trans bc he's a tech dude who also knows how to be empathetic and understanding scorpia is trans bc she's big and strong and scary and just wants to hug everyone and also bc she's an outcast for her physical characteristics entrapta is trans bc being that autistic is trans girl culture catra is a FREAKING CATGIRL cmon here seahawk is trans bc he's super extra and hypermasculine but in a non toxic way mermista is trans bc clearly the reason she's that Done with everything is years of people being dumb about gender obviously netossa and spinnerella are trans bc we don't see enough of them to prove they aren't frosta is trans bc the reason she's so big on following rules and procedures is from being taught how to girl in conclusion: trans
The episode I was just listening to had a scene where Fjord and Beau and Molly all consecutively referred to Nott as a "he", and after each slip up Jester just sorta called out "she!!!" very insistently, and what I'm saying here is yes this, but also, Jester is a really good bean.
Are Homestuck headcanons taboo yet I've invested my self into transmasc Karkat and some flavor of femme GNC/NB Eridan.
The Godseeker from Hollow Knight. It's not even really about her voice, trans women just tend to be Kind Of Like That.
Also Kashima, Kashima is also trans, either a trans dude or some kinda masc-leaning nonbinary. they're a classic case of queer friends who became friends before either one of them knew they were queer
Every male bird cartoon character who's ever laid an egg onscreen is trans or intersex. Same goes for every male kangaroo who has a pouch and every blue huge-tailed female peafowl.
Speaking of, the 2013 Mickey Mouse shorts feature an episode where Mickey and Goofy get shrunk, go inside Donald's body, and end up emerging inside an egg Donald lays. That's gotta be the worst possible way to be outed to your friends.
Looking up various Disney characters for a thing, and one of the Sugar Rush racers from Wreck-It Ralph has a feminine design and a male name (Torvald), so... Not chosen a new name yet?
Shinji is a really complicated character for this, but I think would be a fascinating character to explore re: being a transgirl just because of. a bit of the mess that's going on there. Since Shinji gets a lot of gendered complaints directed that way, a cocktail of being said to be too feminine versus people giving him typical girl complaints like saying he's 'not acting cute'. Maybe not a headcanon inasmuch as a 'I think some of the time that would be a really cool concept to explore, because it is a whole mess there'
After seeing art of Hop for the first time I decided that he was a trans boy, and @Pumpkageist suggested that his deadname was Hope and he just dropped the E.
It is. Leon despairs. He keeps giving Hop baby name books in the hope that he'll pick something better before getting a damn deed poll.