Who Is Linda Hamilton’s Character, Dr. Kay, on STRANGER THINGS 5?

It was exciting news when Linda Hamilton, also known as Sarah Connor from the Terminator movies, came aboard Stranger Things 5. After all, just because it’s the show’s final season doesn’t mean there can’t be some awesome new characters in the mix. And that’s exactly the way we feel about Linda Hamilton’s Dr. Kay after Stranger Things 5, Volume One. Before Stranger Things 5 aired its first episodes, all we knew about Dr. Kay was that she’s a “hyper-intelligent and intimidating” scientist who, if she needs to, can get into a fight and shoot a gun.” But now we know a lot more about this woman, what she’s after, and what surprises she has in store for our heroes. So just who is Linda Hamilton’s Dr. Kay on Stranger Things 5? Join us as we break it all down.

Who Is Linda Hamilton’s Dr. Kay on Stranger Things 5?

In Stranger Things 5, Linda Hamilton’s Dr. Kay has come to Hawkins to ostensibly study the Upside Down, Eleven, and others like her. Although she is a scientist, she is also a feared and fearsome military commander. (A.K.A. she can shoot a gun.) We see Dr. Kay as a Machiavellian character on Stranger Things, she wants to save people and stop the Upside Down, she just doesnt care what it takes to do it. Linda Hamilton’s Dr. Kay isn’t necessarily evil on Stranger Things 5, though she isn’t a good person either. We’ll call her an antagonist.

For example, Dr. Kay was willing to endanger children in Stranger Things 5, Volume 1, by bringing them into the Upside Down. When a subordinate called her out for being reckless, Kay merely challenged him to keep them safe.

What Is Dr. Kay Doing in Hawkins?

In Stranger Things 5, Dr. Kay leads the military compound that the government built inside the Upside Down. The military accesses this compound from the highly secure, off-limits MAC-Z. That’s where a gigantic, building-sized portal to the Upside Down remains open in Hawkins.

Linda Hamilton’s Dr. Kay is also doing her own personal research inside the Upside Down base. Her work includes studying monsters, like the tentacled creature she keeps caged right in the main laboratory. Dr. Kay also made her first appearance on Stranger Things 5, volume 1, while dissecting a giant, bulbous, pulsating, spleen-like organ, which we later learned came from the Upside Down’s flesh wall.

One of Dr. Kay’s chief missions is finding Eleven, whom she believes she “needs.” Dr. Kay thinks locating Eleven is vital because “people are dying, innocent people.” (And presumably, she would also like to study Eleven for her own purposes.)

Dr. Kay Doesn’t Know or Care if Eleven is Good or Bad

Dr. Kay thinks Eleven took the four missing kids in Hawkins (who Vecna actually took) in Stranger Things 5, Volume 1. Kay didn’t know or care if Eleven was trying to kill or protect those children, showing she has no idea who Eleven really is and how she’s involved with the Upside Down.

Dr. Kay Found Eleven’s ‘Kryptonite’—a Sonic Weapon She Developed

In Stranger Things 5, Volume 1, Eleven tries to rip open a path through Vecna’s giant flesh wall by using her powers in the Upside Down when the military shows up. The convoy arrives with a type of sonic blast speaker that completely neutralizes Eleven. Hopper calls the machine Eleven’s “Kryptonite.” Dr. Kay is behind the development of this sonic weapon on Stranger Things 5, clearly hoping it is enough to weaken Eleven and capture her.

The sonic blast all but paralyzes Eleven and causes her to cry out in pain. The moment Hopper knocks the speaker out, Eleven is fine, but she is not prepared for the smaller “Kryptonite” machine located inside the military command center inside the Upside Down.

Dr. Kay’s Mysterious Vault Contains Someone Powerful

After their entanglement with Eleven’s Kryptonite, Hopper and Eleven kidnap the convoy’s unit leader, Akers. The special forces leader claims Dr. Kay “wants the freak,” and that’s all he knows. But Eleven is able to enter his memory and learn more about the lab Kay works in. She uses Akers’ mind to follow Dr. Kay through a secure door at the facility. At the end of the hallway, there is a vault door. Akers says he doesn’t know what’s behind there, but Eleven knows he doesn’t want her to see the “secret shit” locked away. Inside the memory, Eleven used her powers to tear the door off Dr. Kay’s vault. At that moment, Akers passed out.

Eleven shares with Hopper that she’s understood there’s “Kryptonite” behind Dr. Kay’s vault door. She says Linda Hamilton’s Dr. Kay is is keeping someone powerful like Eleven behind it, and that’s how she figured out how to neutralize Eleven with the sonic weapon. Eleven believes Dr. Kay has Vecna locked away in her vault, which is why Hopper wasn’t able to find Vecna during his crawls in Stranger Things 5 and Eleven couldn’t find him with her powers.

The two eventually break into the base, even though Hopper doesn’t think it makes sense that Vecna is in Dr. Kay’s Vault. He assumes the “Kryptonite” that stops Eleven would also stop Vecna. In that case, Vecna never could have taken Holly. But he is willing to go along with the idea and the pair set off to break into Dr. Kay’s compound and vault.

Who Does Dr. Kay Have Trapped in Her Stranger Things 5 Vault?

After a fight with Dr. Kay in her compound, Hopper steals her access key, locks Eleven outside the vault, and enters it, intending to blow himself and Vecna up to ensure Eleven’s safety. Vecna is not behind that door, though. At the same time that Vecna emerges from the MAC-Z’s portal into the real world in Stranger Things 5, Volume 1, Hopper returns from inside the vault.

In the next moment, we and Eleven get to see who is inside of it. The person Linda Hamilton’s Dr. Kay has captured, studied, and locked away in her vault is Eleven’s “sister” Eight/Kali, last seen in season two. We weren’t too thrilled with this surprise Stranger Things 5 cameo, but that’s neither here nor there.

Is Dr. Kay Still Alive at the End of Stranger Things 5, Volume 1?

So is Linda Hamilton’s Dr. Kay still alive at the end of Stranger Things 5, Volume 1? And will we see her return in Volume 2? Yes, is the answer to that. Dr. Kay is still alive at the end of Stranger Things 5, Volume 1.

Before Hopper and Eleven are able to enter the vault, they have a big showdown with Dr. Kay and her soldiers. In the end, Hopper finds himself in the graps of one of the tentacled monster that Dr. Kay studies. Kay explains to him that the creature gets stronger with cold but can’t handle the heat, and she would only free him if she gave up everything he knew. This includes why he would risk Eleven’s life for “the other” powerful figure behind the door (Kali/Eight). Dr. Kay desperately wants to know what Hopper knows that she still doesn’t, but she never gets the chance to find out.

A weakened Eleven emerges, distracts Kay and stabs her, buying enough time for Hopper to escape. He then knocks out Dr. Kay—without killing her. And that’s the last time we see Linda Hamilton’s Dr. Kay on Stranger Things 5, Volume 1.

What Will Linda Hamilton and Dr. Kay Return in Future Episodes of Stranger Things 5?

Given that Linda Hamilton’s Dr. Kay is still alive at the end of Stranger Things 5, Volume 1, we feel certain she will return for Stranger Things‘ final episodes— definitely for Volume 2. Whether she’ll make it out of Stranger Things 5, Volume 2 alive is a different question altogether.

When Dr. Kay awakens, though, will she be more amenable to working with Hopper and Eleven? We bet not. And we’re sure we’ll find out from Kali/Eight that Dr. Kay has not been very nice to her at all.

But, ultimately, we’re glad that Linda Hamilton’s Dr. Kay will return for more Stranger Things 5 episodes. As we said, Dr. Kay is a Machiavellian figure on Stranger Things, someone who is neither wholly good nor wholly evil, a woman who will do anything, no matter how ruthless or dangerous, to keep the world safe. And that’s an interesting character to watch.

Stranger Things 5, Volume 1 is now streaming on Netflix.

Rotem Rusak is Nerdist’s Editor-in-Chief. She recently rewatched all of Stranger Things in 72 hours and is still not over Eddie Munson’s death. If Steve Harrington dies in Stranger Things 5, she will cry.