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, Volumes 1 and 2. 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.) At first, we saw Dr. Kay as a Machiavellian character on Stranger Things, one who wanted to save people and stop the Upside Down, but didn’t care what it took to do it. After Stranger Things 5, Volume 2 though, we’re pretty sure Linda Hamilton’s Dr. Kay is evil of the worst kind.

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.

But, most importantly, Dr. Kay is searching for Eleven on Stranger Things 5. And Dr. Kay is after Eleven for one specific reason—she wants to restart Dr. Brenner’s program and make more psychic kids with the power to access other dimensions.

Dr. Kay Wants to Restart Dr. Brenner’s Program to Harness the Powers of the Upside Down/The Abyss

In Stranger Things 5, Volume 2, we learn that Dr. Kay has absolute tunnel vision on her mission to restart Dr. Brenner’s program and create more psychic kids. She doesn’t care about Vecna, the Upside Down, the Abyss, or anything else. She doesn’t even care that many of her soldiers were massacred during the attack on the MAC-Z. No, all Dr. Kay can see is her search for Eleven. Dr. Kay has been trying to infuse the blood of Kali/Eight, whom she kidnapped, into pregnant women and their babies already. But her experiments have been failing.

However, Dr. Kay believes that with Eleven’s blood, she can make more psychic children, the way that Dr. Brenner created Eleven from Henry/Vecna. Kali shares that Eleven was the only true successful psychic child created from Henry/Vecna’s blood. And so it stands to reason that with her blood, Dr. Kay might stand a chance at being more successful in her efforts to restart Dr. Brenner’s program on Stranger Things 5.

Dr. Kay Wants Demogorgons to Fight the Soviets on Stranger Things 5

But what does Dr. Kay want with more psychic children who can create doors to other dimensions? Well, she wants to use those psychic children to harness the powers of other dimensions and control it. Dr. Kay makes reference to wanting to control Demogorgons so they can fight and kill the soviets in Russia in Stranger Things 5, Volume 2… It feels like Dr. Kay really believes that humans can control the interdimensional powers and that she’ll be able to use them for the US military. Yeah, Linda Hamilton’s character, Dr. Kay, is delusional and evil on Stranger Things 5.

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 the Upside Down’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. We have a feeling we haven’t seen the last of these Dr. Kay-created kryptonite machines on Stranger Things 5… and worry they may ruin the plan to defeat Vecna.

Dr. Kay’s Mysterious Vault Contained Someone Powerful in Stranger Things 5, Volume 1—Here’s What Happened

After their entanglement with Eleven’s Kryptonite in Stranger Things 5, Volume 1, 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. As we mentioned earlier in the article, 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’ Series Finale?

So is Linda Hamilton’s Dr. Kay still alive at the end of Stranger Things‘ series finale? Yes, is the answer to that. Dr. Kay is still alive at the end of Stranger Things‘ final episode.

In Stranger Things 5‘ series finale, Linda Hamilton’s Dr. Kay appears to cause trouble, but she doesn’t have a major role. Mostly, she’s there to remind Eleven that the military will always be haunting her and trying to get her blood for their own purposes. Ultimately, Eleven evades Linda Hamilton’s Dr. Kay on Stranger Things‘ series finale—either by actually dying or by faking her own death in front of her eyes.

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

Given that Linda Hamilton’s Dr. Kay is still alive at the end of Stranger Things‘ series finale, we may just see her again sometime. After all, Dr. Kay is still out there with knowledge of the Upside Down and maybe of the Abyss, if she has all of Dr. Brenner’s studies. Even though she failed to get Eleven, she may just turn up sometime causing trouble for a whole new set of people on her quest for power. But we’ll just have to wait and see.

Stranger Things is now streaming in full 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.

Originally published on November 26, 2025.