Warning: Major Stranger Things 3 spoilers ahead.
Stranger Things viewers had several questions after the heartbreaking season 3 finale: What actually happened to Hopper? Who is “the American”? And…what in the actual hell was that disgusting monster running around trying to kill Eleven and the rest of humanity as we know it? Even after two seasons worth of terror, the Mind Flayer—named after a Dungeons and Dragons monster with supernatural powers, naturally—is a little tricky to comprehend.
After the Mind Flayer took over Will’s body and used him to spy on the gang and Hawkins, season 2 ended with Eleven (Millie Bobby Brown) banishing the monster back into the Upside Down and closing the portal.
This season, Will recognizes its presence in Hawkins pretty quickly via a tingling at the back of his neck. And while he ignores it for a few episodes—understandably not wanting to relive the trauma that comes from a sentient otherworldly force inhabiting his body and mind—the Mind Flayer gets right to work on its evil plan in episode 1 of the third season.
Here’s everything we know about the Stranger Things creature that’s ruined the lives of our Hawkins friends.
What is the Mind Flayer?
First up, that goopy evil thing with giant spider-like tentacles in season 3 is a monstrous new incarnation of the Mind Flayer, the thing from the Upside Down that took over Will Byers’ body (Noah Schnapp) in season 2 and surpassed the Demogorgon as the main Stranger Things monster.
Unlike the Demogorgons and Demodogs, which do its bidding, the Mind Flayer is intelligent and can strategize. Co-creator Ross Duffer explained on an episode of Beyond Stranger Things from 2017 that when figuring out how to continue the series, the writers wanted “something from this other world that was actually sentient”: “We talked about sustaining this story, we talked about Voldemort. You need a threat that wasn’t just a shark. You need a threat that has plans and goals and thoughts.”
Is the Mind Flayer monster in season 3 the same thing as the Mind Flayer from season 2?
Kind of, but not quite. After the Mind Flayer was exorcised from poor Will in season 2 (remember that scary scene with the hot poker?), a small portion of it stayed on earth. From there, the Mind Flayer infected a bunch of rats around town, getting them to congregate in the abandoned Brimborn Steel Works. The inhabited rats feast on fertilizer and other chemicals before exploding into a fleshy, bony goo. (It’s this post-rat evil Mind Flayer goo that hits Billy’s car in episode 1. More on that later!) When those balls of goo all come together, they take the shape of the Mind Flayer monster at the heart of season 3.
What does the Mind Flayer want?
According to what Flayed Billy (Dacre Montgomery) reveals during his final showdown at the end of season 3, the Mind Flayer’s current plan is to kill Eleven because she is its one true enemy and the only force who can destroy it. From there, it presumably wants to destroy the rest of mankind, because that’s generally how evil forces from alternate dimensions tend to operate.
What does the Mind Flayer do?
Back in season 2, we learned that the Mind Flayer uses its hosts to spy on the world at large. That’s what it did when it inhabited Will.
In season 3, we see it take hold of Billy in much the same way, and force him to do its bidding in Hawkins. One by one, Billy brings new townspeople to be infected by the Mind Flayer, and it gradually builds a huge army of people. Killing any of these individual Flayed doesn’t seem to harm the Mind Flayer itself, though—to conquer it, you need to kill its original body.
With the gate to the Upside Down not yet fully open in season 3, the piece of the Mind Flayer that became trapped in Hawkins when Eleven closed the gate at the end of season 2 can no longer send the Demogorgons or Demodogs to do its bad business. Instead, it relies on the creatures readily available in the town, like those rats. Remember when Nancy Wheeler (Natalia Dyer) gets the tip at the newspaper about fertilizer going missing and goes to investigate with Jonathan Byers (Charlie Heaton)? Those rats are beginning to be compromised.
When the couple returns a second time and finds Mrs. Driscoll (Peggy Miley) in the midst of what her editor Tom Holloway (Michael Park)—Heather’s dad—says the hospital deemed a schizophrenic episode, that was the Mind Flayer taking over her body too.
Unfortunately, the bodies that the Mind Flayer takes over tend to explode into a sentient, evil goo that slouches around town. It’s some of that post-rat, Flayed goo that drops on Billy’s car in episode 1, causing him to spin out in front of Brimborn Steel Works and become a human host for the Mind Flayer.
Flayed Billy first sacrifices Heather Holloway (Francesca Reale); the two then go after her parents, and so on until finally an entire lair of zombie-like hosts are standing at attention below the abandoned steel mill in a scene reminiscent of the hosts of Westworld just waiting to be brought to life.
How does the Mind Flayer communicate with and control the monster and the Flayed?
The Mind Flayer seems to be able to communicate telepathically with Billy, directing him to gather more human hosts for him. This seems to be the case for all the Flayed, and is probably the case for the monster as well, which seems to be an extension of the Mind Flayer itself.
Why does it…look like that?
It’s gross! Polygon says The Mind Flayer’s monster “looks like severely waterlogged skin, hardened vomit, and a festering wound all at once.” This is entirely accurate. The Mind Flayer in season 3 takes the form of a gelatinous mound of decomposed bones, flesh, and bad intentions, complete with spidery legs and tentacle mouths. It looks not unlike what you might imagine fatbergs to be before they congeal into a solid, inconvenient mass. (Don’t flush your butt wipes!) It also looks like the visions Will has had of the Mind Flayer, so we can assume its Upside Down form is very similar.
After the Mind Flayer takes over its hosts, the bodies drop onto the floor and decompose into that gross goo, which inches away to join the Mind Flayer monster and make it ever larger. It’s a sight to behold, although we’d really rather not.
Is the Mind Flayer dead?
This time around, the Duffer Brothers said they didn’t want the season to end with Eleven holding her hands up and saving the world. So they have Joyce Byers (Winona Ryder) turn the keys in the Russian underground lab to stop that machine from pumping energy into the void, thereby closing the gate to the Upside Down. The Mind Flayer’s access to our world also gets shut off, so the monster it created dies in the Starcourt Mall (where it had been trying to end Eleven’s life).
It seems that all is well and perhaps we are finished with the Mind Flayer for now. But like with all matters in Stranger Things—all is not what it seems.