While I think these should be seperate timelines as well, I think there should also be a combined timeline of the "Slasherverse".
Texas Chainsaw Massacre
Black Christmas
Halloween
Friday the 13th
Evil Dead
A Nightmare on Elm Street
Child's Play
Shocker
Frozen
Hatchet
Behind the Mask: The Rise of Leslie Vernon
Sharknado
Lavalantula
Let's establish that I'm referring to the Evil Dead films/show, Halloween 4-6, and Texas Chainsaw Massacre 1-4 (and 2022) continuities.
There are many notable ties between the films.
Freddy vs. Jason connects those films indisputably. They must occur on the same timeline. Friday the 13th: The Game contains connections to Halloween, Nightmare on Elm Street, Shocker, Hatchet and Behind the Mask. Rick Cologne is revealed to also be Pastori from Shocker, going under his mother's maiden name. One of the Friday the 13th comics that can fit into canon has a newspaper that states "Leatherface Returns".
Bride of Chucky opens in with a scene in police lockup where various Slashers from other film series are referenced. Michael's mask, Jason's mask, Leatherface's chainsaw and Freddy's glove. This actually can tie into where Halloween 6 left off, with Michael's mask being left on the ground. On a less official note, there was a tv advert where Michael met Chucky.
Behind the Mask: The Rise of Leslie Vernon contains serveral references to Friday the 13th, Nightmare on Elm Street, Halloween and Child's Play. Eugene from Behind the Mask was written to be Billy, the Slasher from Black Christmas.
Hatchet contains references to Leslie Vernon and Jason Voorhees as other in-universe killers. According to the actress, her character from Hatchet 3 is Stretch from Texas Chainsaw 2, though she has a different name. Stretch also appeared in Sharknado despite dying in Hatchet 3. I read that the Sharknado series ended on a timeline reset, so we can assume that the Slasherverse is set in the new timeline, allowing us to ignore Sharknado almost entirely.
Jason Goes to Hell uses the Necronomicon and Kandarian dagger from the Evil Dead series. According to the director, while he couldn't state it outright due to rights issues, he intended to imply Pamala Voorhees used the Necronomicon to resurrect her son, making Jason a Deadite. Jason is also killed by the Kandarian dagger. I imagine that these wouldn't be the same book and dagger from the Ash Evil Dead stories, similar to Evil Dead (2013), and there's multiple copies of the Necronomicon. There's also the Freddy vs Jason vs Ash comic books, but those are set in the Army of Darkness comic universe, where Evil Dead happened in modern day and Ash vs Evil Dead never happened. It also contradicts the continuity of the Friday and Nightmare films in regards to certain characters' ages and other comic books. We can assume a version of the Slasherverse occurred in Earth-818793 like it did in the main universe.
A theory connecting Jason Voorhees to Sam Raimi's Evil Dead franchise is further bolstered by Final Friday director and co-scribe Adam Marcus.
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Caroline Williams made a huge impact with horror fans with her portrayal of DJ Vanita "Stretch" Brock, in The Texas Chainsaw Massacre 2. Her ability to show the vulnerability of the character and convey the terror of someone being tormented by not only a chainsaw-wielding behemoth of a man...
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