Development Work had begun on a third season of
What If...? by July 2022. At that time,
head writer A. C. Bradley revealed that the
second season of the series was her final project at
Marvel Studios, with series story editor
Matthew Chauncey taking over as head writer for the season. Series director
Bryan Andrews returned for the third season along with
Stephan Franck. The season consists of eight episodes. Franck was able to assist Andrews in the season while the latter was simultaneously working on
Marvel Zombies (2025); Andrews was still able to supervise much of the season and ultimately directed three of the season's episodes and co-directed with Franck for one episode, with Franck directing the other four episodes of the season. A
Red Guardian–centered episode, written by Bradley in 2020, is included in the season after originally being intended for the second season. Executive producers for the season include
Brad Winderbaum,
Kevin Feige,
Louis D'Esposito,
Dana Vasquez-Eberhardt, and Andrews. In August 2024, it was announced that the third season would be the series' last. That November, Winderbaum explained that the series was ending due to "bigger [MCU] reasons" that were being determined in real time as different projects were released within
the Multiverse Saga. He said it was the right time for the series to conclude "from a story perspective", but did not rule out
reviving it in the future.
Writing Bradley and Ryan Little served as writers on the season alongside Chauncey. Winderbaum described the season as being the culmination of a trilogy, completing an "emotional experience" with the
Watcher whose humanity is explored more than in previous seasons. He added that the season would have the first hints at "
crossover potential" between the series and Marvel Studios' other animated projects. Some of the unused episode concepts that were created for the
first and second season were used for the third. Andrews said the third season's episode concepts were "wackier" than those used for the first two seasons, and further explore different genres. Episodes include: an
anime-inspired episode featuring the
Avengers piloting
mechs to fight a horde of Mega-
Hulk monsters, titled "Go-Avengers: Heroes of the Gamma War", with Andrews excited to go "full, hardcore, mega genre" with the episode; one with a "1930s
screwball"
Bollywood musical number featuring
Agatha Harkness and
Kingo; one that sees Red Guardian stopping the
Winter Soldier from assassinating
Howard and
Maria Stark and the two becoming allies; one that revisits
Howard the Duck and
Darcy Lewis from the first season episode "
What If... Thor Were an Only Child?", who have since gotten married and must protect their child from various threats; one where an alternate take on the events of
Eternals (2021) leads to the destruction of Earth and the rise of an
authoritarian regime led by
Quentin Beck; and a
Western-themed episode, a genre which Andrews had wanted to explore since the first season. Ideas that were considered for the season but not used include trying to involve the band
Kiss in six different episodes, one of which would have been a galactic
Battle of the Bands concept with Kiss serving as the judges; a
samurai episode that Andrews described as "hardcore and just brutal and awesome" with elements of
Romeo and Juliet; a
Dungeons & Dragons-styled episode; an episode centered on
Sam Wilson and
Yelena Belova where the latter would be the Winter Soldier; and a
kung fu-themed episode featuring
Iron Fist and
Xu Shang-Chi. Andrews also wanted to include the characters
Beta Ray Bill and
Ghost Rider, but Marvel informed him that they were off-limits because they may appear in future projects and wanted to prevent the writers from telling similar stories. Furthermore, despite technically having access to
X-Men characters due to ''
X-Men '97'' (2024–present) being released prior to the season, Andrews and his team were unaware of whether they had permission to do so during development. In retrospect, Andrews expressed regret towards not using
Hugh Jackman's
Logan / Wolverine.
Casting Jeffrey Wright returns to narrate the series as the Watcher. Marvel's plan for the series was to have actors who portray characters in the MCU reprise their roles in
What If...?, with over 35 doing so for the season. These include:
Anthony Mackie as Sam Wilson / Captain America,
Mark Ruffalo as
Bruce Banner / Hulk,
Teyonah Parris as
Monica Rambeau,
Sebastian Stan as
Bucky Barnes / Winter Soldier,
David Harbour as Alexei Shostakov / Red Guardian,
Simu Liu as Xu Shang-Chi,
Oscar Isaac as
Marc Spector / Moon Knight,
Kathryn Hahn as Agatha Harkness,
Kumail Nanjiani as Kingo,
Dominic Cooper as Howard Stark,
James D'Arcy as
Edwin Jarvis,
David Kaye as
Arishem,
Laurence Fishburne as
Bill Foster / Goliath,
Gene Farber as
Karpov,
Kat Dennings as Darcy Lewis,
Seth Green as Howard the Duck,
Samuel L. Jackson as
Nick Fury,
Tom Hiddleston as
Loki,
Clark Gregg as
Phil Coulson,
Michael Rooker as
Yondu Udonta,
Josh Brolin as
Thanos,
Rachel House as
Topaz,
Chris Hemsworth as
Thor,
Tom Vaughan-Lawlor as
Ebony Maw, Hamish Parkinson as
Beerbot 5000,
Dominique Thorne as
Riri Williams / Ironheart,
Emily VanCamp as
Sharon Carter / Power Broker,
Tessa Thompson as
Valkyrie,
Hailee Steinfeld as
Kate Bishop,
Wyatt Russell as
John Walker / U.S. Agent,
Meng'er Zhang as
Xu Xialing,
Walton Goggins as
Sonny Burch,
Hayley Atwell as
Peggy Carter / Captain Carter,
Devery Jacobs as
Kahhori,
Karen Gillan as
Nebula,
Taika Waititi as
Korg, and
Ross Marquand as
Infinity Ultron. Several characters in the season are voiced by different actors than those who portrayed them in MCU films, including:
Kari Wahlgren as
Melina Vostokoff and
Carina,
Brittany Adebumola as
Nakia,
Piotr Michael as
Dreykov,
Kiff VandenHeuvel as
Obadiah Stane,
Matt Friend as
Grandmaster, Jared Butler as
Kaecilius, Andrew Morgado as
Laufey,
Darin De Paul as
Zeus,
Steven French as
Malekith,
Alejandro Saab as Quentin Beck / Mysterio, Kenna Ramsey as
Okoye,
David Chen as
Wong,
Michelle Wong as
Ying Nan,
Fred Tatasciore as
Groot, and Alexandra Daniels as
Carol Danvers / Captain Marvel. Characters introduced in the season include:
America Ferrera as Ranger Morales;
Natasha Lyonne as
Byrdie the Duck;
Jason Isaacs,
D. C. Douglas, and Darin De Paul as a trio of
Watchers named the Eminence, the Incarnate, and the Executioner, respectively; and Allen Deng as
Kwai Jun-Fan. Additionally,
Alison Sealy-Smith voices
Ororo Munroe / Storm the Goddess of Thunder, having previously done so for a different version of the character in the Marvel series
X-Men: The Animated Series (1992–1997) and ''X-Men '97''. Andrews recalled it was Winderbaum's idea to use Storm in the series, as ''X-Men '97'' was going to be released prior to the season so they would have access to all X-Men characters shown in that series.
Animation "What If... the Hulk Fought the Mech Avengers" includes 2D animation inspired by
anime from the 1970s and 1980s, before shifting to the series' usual 3D animation. Andrews hand-animated much of the final fight in "What If... 1872?", working alongside the season's head of animation Scott Wright.
Flying Bark Productions worked on six episodes, and Stellar Creative Lab worked on two episodes.
Music Laura Karpman returned from previous seasons as composer, along with Nora Kroll-Rosenbaum, who composed the score with Karpman for the show's second season. An album was released on January 10, 2025. == Marketing ==