At the end of Season 1, the killer was revealed to be Piper Shaw, who had one last surprise for Emma Duval just before she was killed. We also realized at the end that there was an accomplice since Piper was "attacked" when Will Belmont was kidnapped.
At the end of Season 2, Kieran Wilcox was revealed to have been Piper's accomplice as he was the primary killer in Season 2. However, neither killer exactly said who killed who nor is there clear evidence to all victims on who their killer was. So here is a list of possibilities.
- Nina Patterson - Piper or Kieran.
- Tyler O'Neill - Piper or Kieran.
- Riley Marra - Piper.
- Rachel Murray - Kieran (revealed in Season 2).
- Grayson Pfieffer - Piper or Kieran.
- Will Belmont - Piper.
- Deputy Clifton Roberts - Piper (confessed to the murder in the first season finale).
- Sheriff Clark Hudson - Kieran (confessed to the murder in Season 2).
- All kills in Season 2 (ex. Halloween Special) except one: Kieran,
- 9. Prison Guard: Third Killer, Tom confesses he did not do this.
- 10. Kieran Wilcox: Third Killer, same reason as above.
- All kills in Halloween
Rest of the kills: Tom Martin, he was the sole killer.