Stranger Things 2: Behind the sequel's big, bad 'shadow monster' 

begins with Will (Noah Schnapp) having PTSD-like visions of the Upside Down, including a giant arachnid-like creature that the kids dub “the shadow monster.” “It’s not like others have gone through this. No one has ever gone through this before,” explains Schnapp. “So [Will’s] confused, he’s scared, and he’s trying to cope with everything. You’ll learn in the second season how the Upside Down is affecting him and how it’s kind of changing him.”

Series creators Ross and Matt Duffer wanted to show a different kind of creature after last season’s more simple-minded demogorgon. “Our big reference for [the demogorgon] season 1 was mostly 

It’s a shark and, the other dimension is the underwater. So there has to be something more sentient and that’s that big thing in the sky.”

This “shadow monster” is the major threat that literally hangs above everyone’s heads this season, but at first, viewers won’t know how or why. “I think the difference is you don’t really see how it’s all tied together until later,” Ross says. “But it’s all connected to this singular threat which is tied into this shape that Will sees in the sky. Will is the way through which we’re able to understand what’s going on.”

Inspiration for this new behemoth came from horror classics. Says Matt, “There’s an H.P. Lovecraft sort of approach, this inter-dimensional being that is sort of beyond human comprehension. We purposely don’t want to go too much into what it is or what it wants.”

1 \'This Is Us\' creator breaks down the biggest clue about Jack\'s death

2 \'Avatar 2\': First look at sequel\'s next generation cast

3 How Jack dies: \'This Is Us\' creator, stars on the premiere\'s devastating ending

4 Megyn Kelly asked Jane Fonda about plastic surgery -- and Jane was not having it

5 \'Survivor\' season 35 premiere: Jeff Probst answers burning questions