For nearly twenty years, the Marvel Cinematic Universe has dominated the hearts, minds, and wallets of millions of fans worldwide, producing two of the top five highest-grossing films of all time: Avengers: Endgame in 2019 and, more recently, Spider-Man: Brand New Day (2026)

Part of what made Endgame so successful was how seamlessly it brought to a close the stories of many fan-favorite characters, such as Iron Man (Robert Downey Jr.), Captain America (Chris Evans), and Black Widow (Scarlett Johansen).

And although Avengers: Doomsday (2026) promises the return of many of these characters, the threat they're facing is bigger than ever. Recent talks with Kevin Feige bring mention of a "soft reboot" following Avengers: Secret Wars (2027), but the odds are high that not everyone makes it out of Doomsday in one piece. But who's really on the chopping block?

#1: Thor

Chris Hemsworth's portrayal of the god of thunder is both one of the most iconic aspects of the MCU and one of the oldest, with his 2011 debut marking the fourth movie in the franchise.

Despite his iconicity, Thor has had one of the wildest rides in the MCU, reception-wise. His first solo film released to positive, if slightly underwhelming, results, sitting at a 77% critics' score on Rotten Tomatoes. Two years later, he was given a sequel: Thor: The Dark World (2013), which, though ridiculed for mind-numbing pacing, colorless visuals, and a generic villain, still secured a modest 67% critics' score.

Thor wouldn't receive another solo film until nearly five years later, but it would be his most successful, with Thor: Ragnarok (2017) being everything Dark World wasn't, earning it a strong 93% critics' score. Unfortunately, the last time we saw Thor was in 2022 with Thor: Love and Thunder (2022), which failed miserably at recapturing the lightning in a bottle of its predecessor, ending with a 64% critics' score.

Despite what the performance of his solo ventures may suggest, Thor remains a fan favorite, as audiences have watched him grow from an egotistical warrior to a wise sage, and it is the completion of this arc that makes him ripe for the picking in Doomsday.

The past fifteen years have slowly brought to a close the stories of many of Thor's ensemble characters. His mother, Freya (Rene Russo), died in Dark World, and his father, Odin (Anthony Hopkins), in Ragnarok. The Post-credit scene of Love and Thunder saw his love interest, Jane Foster (Natalie Portman), entering Valhalla after her death, and after two seasons of his own television show, Loki (Tom Hiddleston) has seemingly ascended beyond godhood.

And although Love and Thunder ended with Thor adopting Love (India Rose Hemsworth), the daughter of Gorr the God Butcher (Christian Bale), and the living embodiment of Eternity (man, that movie was weird), many fans are speculating that he'll lose her too, likely to the hands of Dr. Doom (Robert Downey Jr.) himself. This would not only explain Thor's fear of Doom:

"I've fought with many warriors in my time. They were far stronger than all of us put together. And they died. They died facing enemies and threats that scared me far less than this one."

But would also explain his anger:

"I swear, you will beg for hell long before I grant it."

And with trailers focusing heavily on the match-up between Thor and Doom, and Doom blocking Thor's strongest attack with just two fingers, the odds have never seemed bleaker for the god of thunder.

#2: Steve Rogers

One of the best things to come out of the MCU is Chris Evans' portrayal of Captain America, turning what many saw as a one-note, propagandistic protagonist into an inspirational hero who comments on and fights for the ideals of the nation he embodies. In other words, Chris Evans did for Captain America what David Corneswet is doing for Superman.

Despite his beloved portrayal, Evans' ending in Endgame created a divide among the fanbase, with some happy that he finally got his long-awaited dance with Peggy (Hayley Atwell), while others felt that the character, for whom sacrifice is such a core theme, should never have gotten a happily-ever-after.

So when Evans was announced as returning in Doomsday, fans were once again divided: would this be undoing a perfectly satisfying ending, or would it be how we finally get one?

Either way, one thing seems scarily evident: Steve isn't going back to Peggy. Aside from how narratively unsatisfying it would be to have Rogers appear for one movie, help out the team, then go back to how things were, Doomsday directors Joe and Anthony Russo have described the film as taking us "back to phase zero", and when Doomsday wipes the slate of the M.C.U., it's hard to imagine that a Steve who was already on his way out won't get wiped with it.

I should also note that an increasingly widespread theory about Steve's role in the film is that he isn't actually the Steve we know, but rather a villainous variant from another universe working for Doom to gain the Avengers' trust and infiltrate their ranks. While the trailers may lead us to think otherwise, we do see Steve summon Mjolnir from Thor's hand. Perhaps it isn't inconceivable that in an infinite multiverse, Doom has mastered the secrets of Mjolnir's enchantment. In the comics, Doom's abilities come from a powerful mastery of both science and sorcery, and in Thor Ragnarok we saw Hela take command over Mjolnir despite no longer being worthy; perhaps a similar thing is now happening with Evans' character.

Either way, I find it unlikely that whoever Evans is playing makes it out alive. An evil variant is likely to die at the hands of Bucky Barnes (Sebastian Stan) or Sam Wilson (Anthony Mackie), forcing them to kill their best friend and mentor. On the other hand, if this is the Captain America we know, chances are he sacrifices himself for the greater good, appeasing the Endgame naysayers and writing Evans out of the MCU once and for all.

#3: The X-Men... like all of them.

As sad as it is to say, it seems more likely than not that December 18th will be the last time we visit the world of Fox's X-Men.

Mutants have had a long and windy road on screen, with certain standout movies like Logan and X-Men First Class, but also more than a few not-so-amazing movies like Dark Phoenix and X-Men Origins: Wolverine. With roughly thirteen films featuring time travel, reboots and recasts, if any part of the Marvel universe needs a refresh, it's the X-Men.

But that seems to be exactly what they're doing. Slowly, since Endgame, Marvel has steadily been introducing Mutants back into the fray, whether by hinting at the mutation of DNA with characters like Kamala Khan (Iman Vellani), or more recently by featuring iconic X-Man Jean Grey (Sadie Sink) as the lead antagonist in a Spider-Man film.

If that wasn't enough, at the recent D23 event, Marvel announced the casting lineup for Marvel's new X-Men, featuring heavy hitters like Christopher Abbott, Adam Driver, Samara Weaving, and Inde Navarrette.

And while fans are ecstatic to hear about the future of one of Marvel's oldest teams, it begs the question: what about the other guys? I mean, it's not like James Marsden and Kit Connor are both going to be Cyclops going forward; one of them has to move over, and we all know which.

And trailers support this idea, with intense imagery of the X-Mansion in ruins, Ian McKellen's Magneto in tears, and a decimated New York City. This has all lead many fans to believe that the Universe of the Fox X-Men will be among the first to fall at the hands of Doom.

But not all is lost; it seems likely that some Mutants may survive and find their way into the main universe alongside the rest of the cast, namely, Channing Tatum's Gambit, who made a very strong impression in Deadpool & Wolverine (2024). He quickly became a fan favorite, and possibly secured his role in the MCU's future. Speaking of Deadpool & Wolverine, while confirmation of their roles (or lack thereof) in Doomsday is still iffy, the two have firmly established themselves outside the Fox-Cannon, perhaps sparing them from the clutches of Dr. Doom.

It should also be mentioned that there are rumors the X-Men take a more antagonistic role in Doomsday. We've seen them fighting Avengers such as Yelena (Florence Pugh) and Shang-Chi (Simu Liu), and rumored leaks suggest they'll even battle Tobey Maguire's Spider-Man, with the loser's universe being destroyed while the victor's survives.

No matter what role the X-Men play in Doomsday, it's only inevitable that the cast passes the torch to the next generation, as we say one final goodbye to the heroes we love.

As difficult as it may be to reconcile, the fact is that we only have a few more months with many of the characters who have cemented themselves not only within the MCU, but in our hearts.

And while we've said goodbye to some of these characters before, Doomsday brings with it a renewed sense of finality as Fiege prepares the MCU for a major shift following Secret Wars.

So on Dec. 18, as you're shuffling into the theatre, popcorn in one hand, soda in the other, as you settle into your seat next to friends and strangers alike, take a moment to reflect on the time you've spent with these characters. Consider what they've meant to you, and the ways their stories have shaped you. And don't forget the tissues, because saying goodbye is never easy.