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The HBO Max series Stuart Fails to Save the Universe is bringing back some of The Big Bang Theory’s most unlikely heroes.

In the spinoff, which premieres on July 23, a group of supporting characters from the show — including comic book store owner Stuart Bloom (Kevin Sussman), his now-ex Denise (Lauren Lapkus) and Caltech scientists Bert (Brian Posehn) and Barry Kripke (John Ross Bowie) — travel throughout the multiverse to stop an Armageddon event.

In July 2026, co-creator Chuck Lorre addressed his decision to make a side character like Stuart the main star. “He was the absolute worst choice to be the hero of this story, which made him the perfect choice,” he told PEOPLE.

Ultimately, the creators leaned into the absurdity and hilarity of the new show. “When we went out on the limb, on the edge and we were falling off the cliff and we had made horrible, horrible choices, we would just own it,” Lorre said. “If we’re going down this road, let’s commit to this road.”

So, how, exactly, does Stuart Fails to Save the Universe connect to The Big Bang Theory? Here’s everything to know about the links between the shows.

Is Stuart Fails to Save the Universe a spinoff of The Big Bang Theory?

Yes, Stuart Fails to Save the Universe is a spinoff of The Big Bang Theory. But whereas Young Sheldon and Georgie & Mandy’s First Marriage are prequels, focusing on the events before Big Bang, Stuart Fails to Save the Universe picks up after the conclusion of the show.

Sometime after the finale of The Big Bang Theory, Sheldon (Jim Parsons), Leonard (Johnny Galecki) and Howard (Simon Helberg) develop a device that accidentally rips open the fabric of time and space, making it possible to hop between alternate universes within the multiverse — and setting the stage for the events of Stuart Fails to Save the Universe.

What is Stuart Fails to Save the Universe about?

The series begins in an apocalyptic wasteland, in which one of the only businesses still standing — shockingly — is Stuart’s comic book store.

One night while running the shop, Stuart is visited by himself from an alternate universe, who tells him that Leonard and Sheldon have created a quantum interference device that’s wrecked the multiverse — and that it’s up to him to save it from eventual destruction.

From there, Stuart, Denise, Kripke, and Bert stumble through the multiverse, causing havoc everywhere they go. In every alternate universe, everything and everyone is different.

“You imagine each of these worlds and in each of these worlds, there’s a version of you and me, there’s a version of everybody,” co-creator Bill Prady told the Los Angeles Times in July 2026. “They just had a different backstory and a different life because the world was different but you can encounter anyone.”

In each episode, the group must quickly learn what the rules are for each alternate universe and somehow survive it — all while searching for a way to save the world.

What actors from The Big Bang Theory are in Stuart Fails to Save the Universe?

Stuart Fails to Save the Universe is loaded with actors from The Big Bang Theory. The main cast — Sussman, Bowie, Posehn and Lapkus — all reprise their roles from the show.

But fans will also notice that Stuart Fails to Save the Universe is filled with cameos from other actors from The Big Bang Theory. The trailer alone reveals that numerous stars from the original show — like Wil Wheaton, Christine Baranski and the comedy duo Penn & Teller — will be making appearances.

Plus, those involved with the show have teased that even more cameos are on the way. In May 2026, Lapkus told PEOPLE, “There’s a lot of good Easter eggs, throwing back to the first series.”

How else does Stuart Fails to Save the Universe connect to The Big Bang Theory?

On top of the returning characters and storyline, fans of The Big Bang Theory will notice similar settings in Stuart Fails to Save the Universe. Each episode is still set in Pasadena, Calif. — just alternate versions of it.

Stuart’s comic book store and Caltech — where the Big Bang Theory characters worked as scientists — are both recurring settings in the show. In each universe, the spaces look a little “different” than they once did, Sussman told the Los Angeles Times in July 2026.

“The comic book store is our home base for each universe, so every time we were there, you had to feel the old show,” Posehn added.