Every Big Bang Theory Cameo In Stuart Fails To Save The Universe

"Stuart Fails to Save the Universe" just wrapped up its debut season on HBO Max, and it's been a wild ride for fans of "The Big Bang Theory." The series, created by Bill Prady, Zak Penn, and Chuck Lorre, brings Kevin Sussman back as Stuart Bloom, the put-upon comic book store owner seen throughout "The Big Bang Theory" who eventually becomes a series regular towards the end of that show; he's joined by returning players Lauren Lapkus as Denise, John Ross Bowie as Barry Kripke, and Brian Posehn as Bert Kibbler, other supporting characters from "The Big Bang Theory" who make up the main cast of "Stuart Fails to Save the Universe."

So what's the deal with "Stuart Fails to Save the Universe," generally? Unstuck in time and space, Stuart must travel through dimensions and universes — flanked by Denise, Barry, and Bert, who also find versions of themselves living vastly different lives in different timelines — using a device made by original "Big Bang Theory" characters Sheldon Cooper, Howard Wolowitz, and Leonard Hofstadter (Jim Parsons, Simon Helberg, and Johnny Galecki). See, Stuart accidentally damages said device early in "Stuart Fails to Save the Universe," so he has to now prevent what's called "multiverse Armageddon" alongside his friends. What this all also means is that, in different universes, there are plenty of opportunities for original "Big Bang Theory" characters to reprise some form of their roles. Here's every "Big Bang Theory" cameo you get to see on Season 1 of "Stuart Fails to Save the Universe."

So, this one is a bit of a technicality, but let's roll with it anyway. Early in Season 1 of "Stuart Fails to Save the Universe," we see real-life magicians Penn and Teller desperately performing a magic show in one of the more post-apocalyptic scenarios. Penn Jillette has never appeared on "The Big Bang Theory," though he's acted in a fair number of things (including a recent and bizarre turn in the 2025 feel-bad movie "Marty Supreme").

Teller, on the other hand? He plays Larry Fowler, the silent and constantly terrified father of Mayim Bialik's Amy Farrah Fowler. (Kathy Bates portrays his domineering wife.) Here, though? Teller just appears as ... himself, trying to scrape together a little pocket change in a damaged and broken world.

The first returning character from "The Big Bang Theory" that we see is Raj Koothrappali, played throughout the original series by Kunal Nayyar. When the gang finds Raj in that first universe — the post-apocalyptic hellscape — he's being held captive by Barry Kripke, a powerful warlord in this particular world, and he's actually killed by Barry over the device that can transport people throughout the multiverse. Thankfully, that's not the only time we see Raj.

In the season's sixth episode "Spoiler: Corn Is Delicious," which takes place in a universe where everything is more or less the same except that humans function the same way as cows, right down to eating grass, Raj is back ... and he's standing on a street corner yelling about how the multiverse is collapsing and nobody can stop it. While it's distressing to see Nayyar's Raj in these various states of duress, it's still nice to see him, even if he is still stuck being single.

This one is another technicality; there will be a few of those (which makes sense with a show as genre-bending as "Stuart Fails to Save the Universe"). On the original series, living legend Christine Baranski makes semi-regular appearances as Dr. Beverly Hofstadter, the austere and severe mother of Leonard who made her living as a neuroscientist and psychiatrist ... and uses her son as fodder for books about psychiatry. So how does she pop up in "Stuart Fails to Save the Universe?"

As Christine Baranski, actually. In one universe, Stuart and the gang realize that they have implants in their necks that prevent them from ever being rude, fussy, or anything other than aggressively pleasant; when Barry, Stuart, and Bert end up in a sort of prison reformatory meant to make them into happy shiny people, they watch an instructional video where Baranski introduces herself as a lauded actress. Even in this universe, she's right; Baranski has won one Emmy and multiple Tonys as of this writing.

Penny Hofstadter, the character who doesn't initially get a last name on "The Big Bang Theory" and who's played by Kaley Cuoco, dates a few people who aren't Leonard throughout the run of the series ... and one of them is Zack Johnson, played by Brian Thomas Smith. Naturally, he makes an appearance in "Stuart Fails to Save the Universe" alongside Penny herself — we'll come back to her in just a moment — as Penny's lackey in that same universe that featured Christine Baranski's video, where people are punished with electric shocks by an AI-controlled neurochip if they behave rudely or emotionally (calm is the only "acceptable" emotion).

Alongside Penny, Zack is part of the resistance that's able to block the chips, and he's just sort of ... there. Nothing major to report! Zack's just back.

It's nice to see Kaley Cuoco back as Penny, isn't it? A standout of the original series and the only lead female character until Season 4 of "The Big Bang Theory" — when she was joined by Mayim Bialik and Melissa Rauch, and we will also pivot back to those two shortly — Penny appears, alongside Zack, as a high-ranking resistance member who's trying to escape the advent of this AI chip technology. 

Penny, like Raj, also shows up in other universes. In episode 8 — "Spoiler: We're as Confused as You Are" — the main gang is in a universe run by super-strict military forces, and they end up court martialed for treason and given a sentence of death by firing squad. Even though Penny is the one who accused the gang of these crimes, she's also curious about the device ... which leads to a situation where they mistakenly take Penny to a universe where everyone is a centaur. She's ... not super mad about it, actually (and it's a funny little nod to Cuoco's real-life connection to horses, as she's a talented rider and famously loves animals).

Not only is it also great to see the return of Melissa Rauch's diminutive microbiologist Bernadette Rostenkowski-Holowitz (she and Howard Wolowitz get married in the Season 5 finale of "The Big Bang Theory"), but the way that she returns in "Stuart Fails to Save the Universe" is also just really funny. In "Spoiler: Bert Is Magic," the season's third episode, Bert realizes he has magic powers and is viewed as a god; somewhat similarly, Bernadette is a powerful witch who works as a sort of freelance contractor. After Bernadette explains that she needs special ingredients to regain her powers (it's the blood of an innocent), she can help the gang out and create magic to make the device function.

Despite a warning from a different sorcerer, they get Bernadette her blood, and she transforms into a massive demonic version of Bernadette that stomps around and kills half Pasadena in the process. Taking the teeny-tiny Rauch and making her into a Godzilla-esque monster is, frankly, an excellent touch. So who warns the gang about Bernadette's real identity?

The sorcerer who correctly insists that Bernadette is a demon is Wil Wheaton, the "Star Trek" actor reprising his role from "The Big Bang Theory" as, well, Wil Wheaton. Throughout the original series, Wheaton plays a cheeky version of himself who just so happens to be Sheldon's sworn nemesis, and he's always pretty funny. Wheaton only has this one brief appearance in "Stuart Fails to Save the Universe," but it's an excellent nod to his recurring role on "The Big Bang Theory" for fans in the know ... plus, he gets a fun magic battle with Bert.

By the time we see Amy Farrah Fowler — the neuroscientist and Sheldon Cooper's eventual wife and co-Nobel Prize winner played by Mayim Bialik on "The Big Bang Theory" — on this new spin-off, we've already seen Bernadette and Penny, so it's easy to see this coming. Still, the way that "Stuart Fails to Save the Universe" utilizes Amy is pretty clever. At the end of the season's aforementioned third episode, Stuart wakes up in a universe where he's a patient in a mental institution, and his psychiatrist is ... Dr. Amy Farrah Fowler. She is, naturally, skeptical of Stuart's bonkers claims about the multiverse, but when Stuart is told that he's married to Denise and has children with her, he's given permission by the good doctor to go home and recover.

Amy then reappears in the season's penultimate installment "Spoiler: We Couldn't Get Green Lantern" as the girlfriend of Jay Garrick, the Golden Age version of The Flash played by Andy Ridings. Again, it's lovely to see Amy, and she's deployed beautifully on "Stuart Fails to Save the Universe."

While it feels almost silly to include someone who's always played themself in the "Big Bang Theory" universe, the return of Neil DeGrasse Tyson is too important to leave out. The real, acclaimed scientist played himself during the original run of "The Big Bang Theory," and on "Stuart Fails to Save the Universe," his cameo is brief but funny as he's burned at the stake in one particular universe where science is seen as magic ... and witch hunts are a common practice.

Ramona Nowitzki is, canonically, the only woman besides Amy Farrah Fowler in the history of "The Big Bang Theory" to find the irasicble Sheldon Cooper attractive and desirable ... but she gets to play some different beats when she shows up in "Stuart Fails to Save the Universe." Played by the always funny Riki Lindhome, Ramona is the receptionist at the California Institute of Technology, or Caltech the main workplace for the gang during "The Big Bang Theory." In the original series, Ramona is a scientist carrying a torch for Sheldon whose unexpected kiss prompts him to propose to Amy; here, she's simply working a front desk, but she shows up a couple of times to interact with Bert, Denise, Stuart, and Barry.

Joshua Malina, whom you might also know from "Scandal" and "The West Wing," popped up throughout "The Big Bang Theory" as Caltech president Siebert, who finds Sheldon, Leonard, Howard, and Raj annoying but ultimately talented. He ever-so-briefly shows up in "Stuart Fails to Save the Universe" as a military lawyer (a cheeky nod, perhaps, to his role as lawyer David Rosen on "Scandal") in the season's eighth episode, "Spoiler: We're as Confused as You Are."

In the same episode where we see President Siebert as a lawyer, we also see Richard Williams, the Air Force officer who shows up in Season 10 of "The Big Bang Theory" and asks the guys to work on a missile guidance system. In "Stuart Fails to Save the Universe," the Colonel appears as the head of a military force that bullies Stuart, Denise, Barry, and Bert into joining.

Season 1 of "Stuart Fails to Save the Universe" is streaming in its entirety on HBO Max, and if you like that series, here are five other shows you should check out next.