See how Stranger Things built its demogorgon in behind-the-scenes video, photos

It took a lot of work to bring Stranger Things' monstrous demogorgon from the Upside Down to the screen.

Netflix's 1980s-set sci-fi hit is packed with supernatural occurrences and creepy imagery—from Winona Ryder's obsession with Christmas lights to the strange, nightmarish aesthetics of the Upside Down—but the most sinister aspect of the show is the otherworldly monster that Mike, Dustin, and Lucas dub "the demogorgon." With its towering height and head full of sharp, pointy teeth, the creature is pure nightmare fuel, and now, the company behind the monster's creation is sharing a behind-the-scenes look at how it brought the demogorgon to life.

After Stranger Things creators Matt and Ross Duffer worked with concept artist Aaron Sims to design their monster, they recruited a company called Spectral Motion to actually build it, using animatronics to create the demogorgon's strange, horrifying head. This week, Spectral Motion shared footage from their original movement test of the demogorgon's unsettling animatronics.

Spectral Motion also posted some behind-the-scenes photos of the process, including several of demogorgon actor Mark Steger in costume, covered in prosthetics. See the Demogorgon Animatronic Head Test.

Over the summer, the Duffer Brothers spoke to EW about where they found inspiration for their supernatural antagonist and how the demogorgon's animatronic design paid tribute to their favorite movie monsters.

"It has always been something of a lifelong dream to create a monster and bring it to life on-screen," the pair told EW. "Not in the computer but for real. To build it. Like so many filmmakers our age and older, we grew up on genre films that existed before computer graphics. There was something about the effects being so tangible in those films that made them especially terrifying to us when we were kids. We're specifically thinking about Ridley Scott's Alien, John Carpenter's The Thing, and Clive Barker's Hellraiser. So from very early on we knew we wanted to build an animatronic monster."

They added that Spectral Motion went above and beyond in bringing their monster to life.

"The first time we saw our monster's head peel open… it just blew our minds and transported us back to our childhood," the Duffer Brothers said. "And the way it moved was terrifying—their brilliant robotics engineer had designed the animatronics in such a way that the movement of the head 'petals' never repeated themselves. They had a life of their own, moving in unpredictable and bizarre patterns. It felt organic. Creepy. Real."

Read the Duffer Brothers' full breakdown of how they built the demogorgon here.