When it finally arrives on FX this week, American Horror Story 13 could very well boast the biggest cast of characters of any show on the 2026 TV schedule, given that all of the main cast members are playing the multiple roles they’d originated in past seasons. Ryan Murphy revealed early on that Jessica Lange was reprising Constance Langdon from Murder House, and it was later revealed she’s also bringing back her fan-faves Sister Jude, Fiona Goode, and Freak Show maven Elsa Mars. And now there’s a fifth character?!?The Oscar-, Tony-, and Emmy-winning actress appeared on Good Morning America to promote the upcoming 13th season, and while addressing her reasoning for wanting to return, she dropped the huge reveal that she’s actually got one more character up her sleeves. Here’s how she put it in the GMA clip shared to YouTube:I was able to revisit all four of these characters. So that was what kind of interested me to begin with. Also, working with the same [cast and crew]. We were like a repertory company; it was wonderful in that way because we all worked together from one year to another in a different season, different story, different characters. But it really was just the idea of bringing those four characters back. And one mystery character. If I was sitting on that GMA couch where Sam Champion was, I would have sprained my neck doing a triple-take in disbelief. Given all the new-to-the-franchise actors appearing in 13 — John Waters, Madelaine Petsch, Paul Anthony Kelly, Joey Pollari and more — I honestly hadn't considered for a second that the myriad returning stars might be adding new roles to their respective repertoires.After a quick discussion diversion about Langue getting an upcoming musical number, she was asked directly about the big reveal. She obviously didn't spill the beans right then and there, but did say:There is a fifth character, but I won’t say who that is. But I’d be curious if anybody can figure it out when it…It's hard to read too much into her wording, though it is particular enough to spark some thoughts. Because it sounds like it'll be a person (or other entity) of note that may already be familiar in the real world. Because if she's just playing a random librarian named Tallulah, I'm not sure how anyone even would be able to figure that out. Because Jessica Lange let her final word linger as one of GMA's presenters started talking again, it's unclear where the rest of that sentence was going. She may have been implying fans may not be able to "figure it out when" she's on the screen as the character, which could indicate that she'll be wearing a mask or will have heavy prosthetics and makeup on. So with that in mind, here are some quick theories about who Lange's fifth mystery character could be. Theory #1: A Supernatural Or Religious God/GoddessWith the first full-length AHS 13 trailer seemingly revealing a full-on demon, it's possibly Lange will factor into that story in a new way. Probably not specifically a Christian God, given she's already playing a nun, but possibly a goddess aligned with or against the world of Voodoo. With the surprise addition of Orlando Jones as Papa Legba, taking over for the late Lance Reddick, could we see Lange portraying a friend or foe of Angela Bassett's Marie Laveau? Or perhaps this season will put the focus on another belief system. Theory #2: Belle Gunness Or Another Historical Killer (Or Victim)With the return of Mena Suvari as Black Dahila Elizabeth Short, as well as Zach Villa's Richard Ramirez and potentially more killers and victims from America's past, could Lange be portraying someone in that vein? I like the odds of Belle Gunness, an immigrant suspected of potentially killing up to 40 people in the first decade of the 1900s. The barn where she lived burned down before authorities could make a case against her, but the farmhand initially convicted with setting the fire said she ordered him to do it as a way to fake her death. So could Lange show up as Gunness years after she was initially thought dead? Or something else in that realm?Theory 3: Someone From Twisty's WorldIn the Season 13 trailer, it appears as if Twisty goes into attack mode on a group of presumably non-supernatural clowns, but without much context to it. If Lange is indeed cloaked under makeup for the mystery character, could she be involved with that group of clowns? OR, if any of the episodes dip back into Twisty's past, could Lange take on the role of the eventual clown's alcoholic mother?Theory #4: Jessica Lange HerselfIf one reads into all of Jessica Lange's comments as being entirely tongue-in-cheek, from calling it a "mystery" to wondering if fans will guess it, I think it's not impossible to believe that the actress could be playing a heightened version of herself in the season. Seems a little silly, but that's just this franchise. I guess I'll stop here, since my theories could very easily devolve the point where I'm guessing characters from completely different TV shows making crossover appearances. American Horror Story 13 will kick off its star-studded run on FX on Thursday, September 24, at 9:00 pm ET with the first three episodes. It'll also stream the next day via Hulu and Disney+ subscriptions.