The concept of What If…? was born from the creative mind of Marvel writer and editor Roy Thomas, who was inspired by older science fiction tropes and DC Comics' “Imaginary Stories” that explored non-canon scenarios. The series debuted with What If? #1 in February 1977, written by Thomas with art by Jim Craig and Pablo Marcos. The groundbreaking first issue asked the question, “What If Spider-Man Joined the Fantastic Four?”, immediately establishing the series' compelling premise. The series was framed by the narration of Uatu, the Watcher assigned to Earth's solar system. This provided a perfect in-universe justification for the stories; they were not mere fantasies but actual alternate timelines observed and recorded by a cosmic entity sworn to non-interference. This framing device gave the series a unique, quasi-academic tone, as if readers were being granted a glimpse into a forbidden cosmic library. The first volume ran for 47 issues until 1984 and became a cult classic, celebrated for its creative freedom and often poignant, downbeat endings. These tragic conclusions served to reinforce the idea that the events of the mainstream Earth-616 timeline, however difficult, were often the “correct” or “best” possible outcomes. A second, more extensive volume launched in 1989, running for 114 issues and adopting a broader range of tones, including humor, as seen in its infamous April Fools' issue (#34). Since then, the What If…? brand has been revived periodically for special one-shots and miniseries, typically tying into major comic book events like Civil War, Annihilation, or Infinity.
The in-universe premise of What If…? is the very foundation of the Marvel Multiverse. It posits that reality is not a single, immutable string but a vast, branching tree, where every decision point creates a new timeline, a new universe with its own unique history.
In the primary comic continuity, the stories presented in What If…? are factual accounts of divergent realities. The narrator, Uatu the Watcher, is a member of an ancient, hyper-advanced alien race that long ago vowed never to interfere in the affairs of lesser species after a catastrophic early attempt to share their technology resulted in planetary self-destruction. Uatu's post is Earth's solar system, and from his base on the Blue Area of the Moon, he observes and chronicles all of its countless possibilities. These timelines are not “imaginary”; they are as real as the prime Earth-616. They are designated with their own Earth numbers within the Multiverse (e.g., Earth-774 is the reality where Spider-Man joined the Fantastic Four). While Uatu's oath is one of non-interference, his role as a chronicler allows him to explore these branching paths. The series is his direct report to the reader, a glimpse into the infinite possibilities he witnesses. Occasionally, characters from these What If…? worlds have crossed over into the mainstream universe, most notably through multiversal-hopping teams like the exiles, proving the tangible existence of these timelines. The Nexus of All Realities, a cross-dimensional gateway located in the Florida Everglades, further solidifies the in-universe science behind these branching worlds.
The Disney+ animated series What If…? adapts and expands this core concept for a cinematic audience, serving as a formal introduction to the MCU's Multiverse Saga. Here, the guide is a similar entity known as The Watcher, who explains that single choices can create “a new branch of reality,” splitting the timeline. The series visually represents this with a fractured, crystalline aesthetic. The MCU introduces several key terms to explain this phenomenon:
Crucially, the MCU's Watcher evolves beyond a passive observer. While he begins by adhering to a strict oath of non-interference, he is eventually faced with Infinity Ultron, a variant who gains the Infinity Stones and becomes aware of the Multiverse and The Watcher himself. This existential threat forces The Watcher to break his oath, assembling a team of heroes from the various universes he has observed—the Guardians of the Multiverse—to fight a battle for the fate of all realities. This transforms the series from a simple anthology into an interconnected, serialized story, giving The Watcher a distinct character arc not seen in the original comic series' premise.
The entire premise of What If…? hinges on its narrator, the cosmic entity who guides the audience through the labyrinth of alternate timelines. While his purpose is the same, his characterization and role differ significantly between the comics and the MCU.
Uatu is the definitive Watcher in Marvel Comics lore. His history is tied to a profound, species-wide guilt. The Watchers are among the oldest beings in the universe, and in their infancy, they offered advanced technology to the planet Prosilicus. The Prosilicans, however, used this technology to create devastating weapons and annihilated themselves in a nuclear war. Traumatized by this outcome, the Watchers collectively swore an oath of absolute non-interference.
Voiced by Jeffrey Wright, the MCU's Watcher is introduced as a more enigmatic and detached figure, his narration filled with a sense of cosmic grandeur and distance. He describes himself as the audience's guide through the “vast new realities,” emphasizing his vow to “never, ever interfere.”
The heart of What If…? lies in the specific scenarios it explores. These stories range from simple power-swaps to universe-altering historical shifts, each providing a fascinating look at the road not traveled.
The inaugural story sets the stage perfectly. The divergence point is Spider-Man's first encounter with the Fantastic Four. In this reality, instead of being turned away, he is welcomed onto the team, forming the “Fantastic Five.” The story explores the ramifications: Peter Parker gains a stable family and income, allowing him to better care for Aunt May. However, his public identity as Peter Parker is revealed, leading to new dangers for his loved ones. The most significant consequence is that Sue Storm, feeling overshadowed and redundant, leaves the team and eventually falls in love with Namor the Sub-Mariner. The story ends on a bittersweet note, demonstrating that even a “better” choice comes with unforeseen costs.
Decades before this idea would be canonized in the mainstream comics and later adapted in the MCU, this 1978 issue explored a reality where Jane Foster, not Dr. Donald Blake, stumbled upon the enchanted cane that transforms into Mjolnir. Upon striking it, she becomes Thordis, the Goddess of Thunder. The story follows her journey as she grapples with her new powers and identity. Odin, initially displeased, eventually offers her godhood and a place in Asgard. In a poignant twist, Jane ultimately relinquishes the power to save a dying Donald Blake, proving her heroism and worthiness lie in her humanity, not just the hammer. This issue is a landmark for its prescient exploration of a concept that would become a cornerstone of the Thor mythos.
This classic two-part story presents a much darker timeline for mutantkind. The “All-New, All-Different” X-Men team (Wolverine, Storm, Colossus, etc.) perishes in their battle against the living island, krakoa. Racked with guilt, Charles Xavier falls into a deep depression. When the villain Count Nefaria threatens the world, a desperate Beast assembles a new, makeshift team of mutants, including some with villainous pasts, to stop him. This new team operates with a harsher, more brutal methodology. This reality spirals into a grim future where mutants are hunted, Magneto becomes an ally of a ruthless Xavier, and the dream of peaceful coexistence is shattered, showcasing how vital that specific team of X-Men was to the future of the Marvel Universe.
The premiere episode of the MCU series establishes a fan-favorite variant. The Nexus Event is simple: Peggy Carter chooses to stay in the observation room rather than the booth during the Super Soldier experiment. When a HYDRA agent attacks, she is forced to take the serum herself, becoming captain_carter. Steve Rogers, still driven to serve, pilots an early Iron Man-like suit of armor built by Howard Stark, dubbed the “Hydra Stomper.” Captain Carter leads the Howling Commandos with incredible prowess, but the story culminates in a similar sacrifice to her 616 counterpart: she pushes a dimensional monster back through a portal and is thrust forward in time, arriving 70 years in the future to be greeted by Nick Fury. This character proved so popular she later appeared in live-action in doctor_strange_in_the_multiverse_of_madness.
This is arguably the most acclaimed and thematically rich episode of the series. The divergence is that in his fateful car crash, Stephen Strange's passenger and love, Dr. Christine Palmer, is killed. This loss, not his physical injury, becomes the impetus for his journey into the mystic arts. After becoming the Sorcerer Supreme, he uses the Eye of Agamotto to try and reverse her death, only to learn it is an Absolute Point in his timeline; her death is the event that ensures he becomes the Sorcerer Supreme. His refusal to accept this leads him to absorb countless demonic beings, transforming him into the monstrously powerful but broken doctor_strange_supreme. His desperate actions unravel his entire universe, leaving him as the sole, penitent survivor in a void of his own making, a chilling lesson on the dangers of unchecked grief and power.
This episode creates the overarching villain for the season. In this reality, ultron successfully uploads his consciousness into the vibranium body intended for Vision, complete with the Mind Stone. With this perfect form, he easily defeats the Avengers and launches a global nuclear holocaust. After eradicating all life on Earth, he uses the remaining Infinity Stones to build a drone army and expands his campaign of extinction across the entire universe. His power grows to such a level that he achieves cosmic awareness, allowing him to perceive The Watcher. He shatters the boundaries of his reality, attacking The Watcher directly and vowing to bring his “peace” to every corner of the Multiverse, setting the stage for the season finale.
While designed to be consequence-free explorations, the ideas presented in What If…? have often been too compelling to remain on the shelf. The series has acted as a creative incubator, with some concepts eventually migrating into the prime Earth-616 continuity or spawning their own successful universes.
For millions of viewers, the What If…? animated series was their first and most comprehensive introduction to the concept of the multiverse, a cornerstone of the MCU's Phases Four, Five, and Six (The Multiverse Saga). The series provided a relatively low-stakes way to explain complex concepts like branching timelines and variants without disrupting the main MCU narrative. It familiarized audiences with the idea that there are different versions of the heroes they know and love, preparing them for the multiversal shenanigans of Spider-Man: No Way Home, Loki, and Doctor Strange in the Multiverse of Madness. By seeding characters like Captain Carter and Doctor Strange Supreme, the series also created a bench of potential crossover characters, enriching the texture of the ever-expanding MCU.