Stuart Fails to Save the Universe is an American science fiction comedy series created by Chuck Lorre, Zak Penn, and Bill Prady, serving as the fourth show in The Big Bang Theory franchise. The plot follows Stuart Bloom (Kevin Sussman), who, after accidentally breaking a device built by Sheldon, Leonard, and Howard, must prevent a "multiverse Armageddon" while meeting alternate versions of himself and his friends. The series features returning cast members like Brian Posehn, Lauren Lapkus, and John Ross Bowie, alongside special guest stars including Kaley Cuoco, Mayim Bialik, and Wil Wheaton. After being announced in 2023 and officially ordered in July 2025, the show premiered on HBO Max on July 23, 2026, and was quickly renewed for a second season in August 2026. Lorre described the project as a challenging departure from his usual sitcom style, embracing special effects and action-adventure elements. The series currently holds a 77% approval rating on Rotten Tomatoes based on 43 reviews.