Episode 8 of Marvel's spin-off series What If...? features an impressive cast of new and returning MCU characters. The story includes not only the return of popular members of the Avengers, but also characters assumed to have faded into obscurity after previous What If...? episodes. As a result, this installment perhaps provides the most important connection yet between the show and the so-called sacred MCU timeline.

Unlike many previous episodes, this particular What If...? storyline exposed the fraught connections between Marvel's innumerable alternate universes. Instead of offering a low-stakes stand-alone story, episode 8 presented a scenario in which Ultron successfully integrates with the Mind Stone-powered Vision body and consequently takes over the Earth. He then proceeds to destroy all life in the known universe in a quest for peace, before advancing on the multiverse. This eventually brings the genocidal AI into direct conflict with The Watcher, who is finally forced to turn to the evil Doctor Strange seen earlier in the series for assistance.

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The plot brings a genuine sense of jeopardy to the series as Ultron's expansion into the multiverse potentially puts everything, including the sacred timeline, in danger. However, because of Ultron's annihilation of many key Marvel characters, the ensemble cast is nowhere near as extensive as many previous episodes. Nevertheless, there is still no shortage of major players on display. Here is every new and returning character from What If...? episode 8.

The Watcher – Jeffrey Wright

An ever-present throughout the series, episode 8 is the first time that Jeffrey Wright's Watcher is brought directly into the action. As Ultron becomes aware of the multiverse, he comes into direct conflict with The Watcher, engaging in an interdimensional conflict that forces the celestial being to turn to evil Doctor Strange for help. This is by some distance the most active Wright's character has been in the series so far, having until this point only been a casual observer. However, this new role suggests that The Watcher may be even more prominent in future episodes.

Clint Barton/Hawkeye – Jeremy Renner

While Renner will return to the live-action MCU in the upcoming Hawkeye series, his iconic Clint Barton character also crops up on several occasions throughout What If...? Before episode 8, for instance, Barton also featured in episode 3, where he was inadvertently responsible for killing Thor thanks to the nefarious actions of an evil Hank Pym/Yellowjacket. Renner has been a vital part of the MCU since Phase 1, first appearing in an uncredited cameo in 2011's Thor.

Doctor Strange/Strange Supreme – Benedict Cumberbatch

After seemingly dooming himself to an eternity of imprisonment, What If...?'s evil version of Doctor Strange, played by Benedict Cumberbatch, returns to the action in episode 8. The fallen sorcerer, who caused the collapse of his own universe by attempting to undo a fixed point in time, seems to be integral to any attempt to defeat Ultron and will undoubtedly feature prominently in the rest of the series. Cumberbatch himself will also feature in upcoming MCU entries Spider-Man: No Way Home and Doctor Strange In The Multiverse Of Madness.

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Natasha Romanov/Black Widow – Lake Bell

Red Hot American Summer Lake Bell

As in episode 3 of What If...?, Natasha Romanov (AKA, Black Widow) is a crucial protagonist in the fight against the forces of evil. Voiced here by Lake Bell, the character fights alongside Barton and Arnim Zola to upload the German scientist's digital consciousness into an Ultron drone in an effort to stop the megalomaniacal AI. Given the well-publicized conflict between Scarlett Johansson and Disney, it may seem as though the original Black Widow's absence is particularly poignant. However, reports suggest that Bell has stepped in as a result of a scheduling conflict, rather than anything more pointed.

Arnim Zola – Toby Jones

Despite his apparent destruction during the events of Captain America: The Winter Soldier, Toby Jones' Arnim Zola returns to the MCU in What If...? episode 8. After being unearthed by agents Barton and Romanoff, it is revealed that Zola may be integral in stopping Ultron from destroying the multiverse, potentially placing Zola on the side of good. Beyond Marvel, Jones himself has enjoyed a hugely prolific career, starring in dozens of movies ranging from the Harry Potter saga to Jurassic World: Fallen Kingdom.

Ultron/Sub-Ultron Sentries – Ross Marquand

Ultron What If Ross Marquand

Taking over Ultron duties from the previous incumbent James Spader, Ross Marquand is no stranger to playing supervillains in the MCU. Not only does he voice the supremely powerful robot in What If...?, but Marquand also served as Hugo Weaving's replacement in the main MCU timeline, portraying the Red Skull in both Avengers: Infinity War and Avengers: Endgame. In addition to his work with Marvel, Marquand is probably best known as Aaron from hit horror series The Walking Dead.

Steve Rogers/Captain America – Josh Keaton

Josh Keaton Captain America What If

Much like his former Avengers co-star Robert Downey Jr., Chris Evans elected not to return to the MCU for What If...? Instead, the role of Steve Rogers has been taken on by Josh Keaton. The well-known voice actor has played a number of prominent roles in the past, including various characters in different animated Spider-Man adaptations.

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Tony Stark/Iron Man – Mick Wingert

Tony Stark What If Mick Wingert

While Wingert is filling in the sizable void left by Robert Downey Jr. throughout the current series, this isn't the first time he has taken on the role. In addition to his various appearances in What If...?, Wingert has also voiced both Tony Stark and Iron Man in several other TV and video game Marvel adaptations. Although his appearance in episode 8 is comparatively brief, Stark's role in creating Ultron means it is still an incredibly important part.

Carol Danvers/Captain Marvel – Alexandra Daniels

Alexandra Daniels Captain Marvel What If

Due to scheduling conflicts, Brie Larson couldn't return as Captain Marvel for the current series. Instead, voiceover duties have been conducted by Alexandra Daniels, a voice and screen actor whose most prominent previous role was probably in the 2016 movie Mothers and Daughters. Despite Daniels' deputizing during What If...?, Larson will return to the role in the upcoming sequel film The Marvels.

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