Evidence: In addition to being incredibly forthcoming about her disdain for the current Kappas — as well as the current generation in general — Dean Munsch is also (allegedly) an expert at covering up heinous acts. Plus, how else can she "guarantee" that Grace won't be a target for the Red Devil?
Evidence: Presumably the child born to the dead Kappa in 1995, Pete is also (conveniently) Wallace University's mascot, meaning he has a Red Devil costume at the ready. Couple that with his Chanel No. 1 obsession and the fact that he can't end a scene without flashing the camera a super creepy smile, and you've got yourself a recipe for DUH!!!
Evidence: Besides Dean Munsch, the only other person confirmed to have been present for the death of the Kappa girl in 1995 was Ms. Bean. And let's not forget: "Nothing happens in this house without [Ms. Bean] knowing about it."
Evidence: Hester's obsession with death, coupled with that villainous neck brace, makes her an automatic suspect. Also, is it possible that she calls Chanel "mom" not because it's a current fad, but because she's the child of the girl who died in 1995 and she's constantly seeking a mother figure in her life?
Evidence: According to her therapist, Gigi suffered a traumatic experience that kept part of her psyche "forever trapped in the '90s." So is it safe to assume that she was one of the Kappas whose friend died in the bathtub? And is it also possible that said traumatic experience is causing her to black out, kill Kappas, then immediately forget? Hey, you never know.
Chanel Oberlin (aka Chanel No. 1)
Evidence: Chanel claims she was attacked by the Red Devil, but we only saw them interact via her story. Isn't it possible she trashed her own room, spray painted "SLUTS WILL DIE" on the wall, then screamed for the girls to come see it?
Chanel No. 5
Evidence: Unlike the other Chanels, who seem comfortable taking a back seat to Ms. Oberlin, No. 5 clearly had leadership aspirations. And we all remember how No. 1 became No. 1, right?
Evidence: I know Scream Queens isn't exactly based in reality, but Chad didn't seem too torn up when he announced the "death" of his best friend/spooning partner Boone. And given the raging broner Boone has for Chad, it would make sense that he'd willingly assist him with anything — including, say, a crazy plan to off all the Kappas.
Evidence: I'm not convinced that Wes isn't the revenge-seeking father of the baby born in the Kappa bathtub in 1995, regardless of whether it's Pete or not. (Side note: I'm really hoping it isn’t Pete. Incidental incest is not a thing I want this show to explore.)
Evidence: As far as I can tell from the first two hours, there's no evidence with which to point a finger at Grace — but this is a Ryan Murphy show and an anthology, so couldn't you see it ending with a nonsensical Grace-is-the-killer reveal anyway?