Marvel's first animated show, Scarlet Witch and Loki is that it's harder to get people like Scarlett Johansson, Benedict Cumberbatch, and Chris Evans to commit to longer-term productions.
A-listers of that caliber are constantly fielding movie offers, and if they were actually willing to commit to starring in a Disney+ show, their asking price might prove prohibitive for Marvel Studios in a way it wouldn't when casting them in a theatrical release likely to earn truckloads of money. Providing a voice for an animated show isn't as big a time commitment, but most fans were under no illusions they wouldn't hear Robert Downey Jr. on What If...?.
In Marvel Studios' defense, they were successfully able to sign on a staggering percentage of actors from the MCU to reprise their roles in voice form, including Chris Hemsworth, Paul Rudd, Mark Ruffalo, Samuel L. Jackson, and the late Chadwick Boseman. Here's the full rundown of the characters whose actors didn't make the jump, and needed to be recast.
Iron Man/ Tony Stark
Tony Stark appears in a number of What If...? episodes, and is killed off in no less than three. The first sees him murdered by Yellowjacket, the second is a take on Marvel Zombies and the third presents an alliance between Erik Killmonger and Tony after the former rescues him following the terrorist attack seen in the first movie. Standing in for Robert Downey Jr. as Tony on What If...? - and doing a very good sound-alike performance - is Mick Wingert, who has pulled understudy duty for Robert Downey Jr on multiple animated projects already.
Captain America/Steve Rogers
Steve Rogers appeared both in Peggy Carter's Captain Carter episode and also the Marvel Zombies episode, with only a vocal performance in the former. Hayley Atwell returned as Peggy, but it's not too surprising that Chris Evans isn't a part of What If...?, as whether he's a current part of the MCU at all anymore is unclear. In What If...? Cap is voiced by Josh Keaton, who has years of experience on vocal work. Credits include voicing Young Hercules in Hercules (1997), Takashi 'Shiro' Shirogane (a.k.a. "Space Dad") in Voltron: Legendary Defender, and Peter Parker The Spectacular Spider-Man animated TV show.
Captain Marvel/Carol Danvers
Captain Marvel first appeared in What If...? briefly in the Avengers Murders episode in the wake of Loki's invasion of Earth, answering Nick Fury's call to help. Brie Larson didn't return to voice her, despite still being under contract to the MCU, and set to return for Captain Marvel sequel The Marvels in 2022. It's possible Larson just had a scheduling issue. Instead, she's played by relative newcomer Alexandra Daniels.
Black Widow/Natasha Romanoff
Alongside several of her original Avenger co-stars, Scarlett Johansson did not reprise her role as Black Widow in the animated series of What If...?. The Black Widow-centred episode sees her as the last survivor of Yellowjacket's nefarious scheme to wipe out the Avengers. After her appearance in her long-overdue solo outing as the titular heroine in Black Widow that has been the source of much legal controversy, it is potentially unlikely that fans will see Johansson returning as the international superspy anytime soon in the MCU, though this won't have played a part in her What If...? absence. Nat is played incredibly well - to the extent it sounds like Johansson did return - by comedian Lake Bell.
Spider-Man/Peter Parker
Tom Holland did not return as Spider-Man for What If...?, ing his Avenger allies on the absentee list. The Web-Head would have been the focus of an episode that featured him as a zombie hunter, attempting to help the survivors escape the clutches of the undead Tony Stark and Captain America monsters. As for why Holland did not return for the series, one could speculate that it has to do with scheduling conflicts alongside Sony, though the real reason remains a mystery. He's replaced by Hudson Thames.
Drax The Destroyer
Drax is also not voiced by the outgoing Dave Bautista. The actor has spoken at length about speculation regarding his future in the MCU after the much-anticipated director James Gunn. Drax appears briefly in the episode addressing, "What if T'Challa was abducted by Yondu instead of Peter Quill?" He's played instead by veteran voice actor Fred Tatasciore.
All Other Characters Recast In What If...?
General Ross - Despite returning in Phase 4's opener Black Widow, William Hurt does not reprise his role as Thunderbolt Ross in What If...? Instead, he's played by Michael Patrick McGill.
Betty Ross - Having reappeared after The Incredible Hulk, Betty Ross is played by Stephanie Panisello rather than Liv Tyler.
Obadiah Stane - The Iron Man villain returned for Killmonger's What If...? episode, played not by Jeff Bridges, but by Kiff VandenHeuvel.
Pepper Potts - Tony Stark's wife also returned for Killmonger's episode and is not played by Gwyneth Paltrow but by Beth Hoyt.
Peter Quill - He appears only very briefly at the end of T'Challa's Star-Lord episode, but Peter Quill was voiced by Brian T Delaney and not Chris Pratt.
Shuri - Played by Letitia Wright in Black Panther and the sequel Wakanda Forever, T'Challa's genius little sister is played in What If...? by Ozioma Akagha.
