Ok theory time, because I was bored!
The more the story evolves, the more people I cross out to be the killer
Dean Munsch - too obvious since the start, and now the final monologue scene where she said- this is the perfect time to murder her husband when there's a serial killer on the loose... there's no way she's the killer now.
Grace - I thought she was the killer after a while! Aside that no one suspects her, she overheard Chanel's plan with Ms. Bean at the coffee shop, she knows Grace loves Oakland Nachos, and her excuse why she wants to join Kappa is messy, she's probably being snoopy to make people think otherwise about her.
However, her scene with Gigi on episode 7 makes me think she is not the killer. Unless she's actually the
Uber A and Gigi doesn't know.
Grace's Dad - Someone said it a few pages back. I thought he is somehow involved but Gigi is still being secretive of her plans to him.
The Chanels - They were so convinced @ the Ouija board saying Chanel is the killer. Unless 1 of them controlled that glass thing (if someone did, my money is on Hester), but that would make Number 2's confession in Chanel's dream EXTRA silly.
Sidebar: Number 5 has got to be very psycho to agree with killing Roger and Dodger, when she's been waiting years for some guy to like her lmao. When she said she's only in Kappa because she's a legacy means there's more to the story why she's here, though.
of course some of them could be the killer, still. But it will just be messy. Then I remember this is a Ryan Murphy show. It WILL be messy.
that leaves me to just 1 person who could really be one of the killers, but an irrelevant one.
Earl
- i assume when Gigi was talking on the phone, it was with Boone. when she said "we are not kidnappers, we are murderers.. he's gotta go" etc I think it was about Earl kidnapping Zayday instead of killing her. And he wants Boone to get rid of him, but this is just a guess! Basically, they are just accomplices. Would make sense too since Earl & Boone are barely on screen and gives them enough excuse to be there at every killings.
I want them to surprise me though.
Earl
will be so boring unless there's a really great backstory.
and there's that stuff about her being a legacy too.
Bologna 
