The MCU may be about to make huge changes to comic book lore with Robert Downey Jr.’s casting as Doctor Doom – but it can be easy to forget that Iron Man established this precedent. Iron Man launched the MCU into the stratosphere in 2008, preceding nearly two decades of iconic Marvel Comics adaptations that are still going strong with Deadpool & Wolverine being its most recent triumph. Nevertheless, it is impossible to ignore the apparent effect that Robert Downey Jr.’s departure has had on the MCU.

This has led many to surmise that Robert Downey Jr.’s MCU return has been orchestrated to help recapture the incredible success of the Infinity Saga. While this remains the most cynical reasoning behind Marvel’s decision to recast RDJ, there is no denying that having someone who is arguably the MCUs most famous contributor embody a role as iconic as Doctor Doom raises many questions about how faithfully the franchise can adapt Doom in 2026’s Avengers: Doomsday. The fact, however, is that Marvel is proficient at making changes to established lore for the better.

Marvel Aren’t Scared Of Changing Comics Stories

The MCU Alters Multiple Origin Stories

The MCU is generally faithful to its comic book origins, particularly when it comes to character design. The most recent example of this can be found in Deadpool & Wolverine. Whereas the X-Men franchise was hesitant to faithfully depict the titular team in their classic costumes, even going so far as to address the changes with a cynical joke by Cyclops, it took a migration to the MCU for Wolverine to finally don his classic yellow and blue suit complete with sheaths for his claws. 24 years after Wolverine debuted in live-action, the decision went down a storm.

Even still, the MCU is no stranger to taking creative liberties. Just a few examples of its alterations to established lore include the origins of the Maximoff twins, the origins of the Infinity Stones and the minutia of their powers, and the various situations that have seen Tony Stark fill the shoes of Hank Pym, such as with the creation of Ultron. The results of these minor changes speak for themselves, with the Infinity Saga playing host to 9 of the MCU’s 11 billion-dollar movies.

These alterations have arguably ramped up in the Multiverse Saga. Kamala Khans’s powers and mutant genes were revealed in her debut series and flew in the face of her comic book origins. Namor, meanwhile, is practically an original character when comparing his MCU and comic book iterations. Unfortunately, these new directions have also given rise to the MCU’s worst-rated series as it morphed the narrative on which Secret Invasion was based to an unrecognizable degree, while MODOK was also changed for the worse.

This all shows how changing comic book lore is par for the course in the MCU as an active creative decision. At various times, Marvel creatives, including James Gunn, have broken cover to defend the changes to the source material as simply doing what’s best for their own stories. Ignoring the sanctity of the comics is now part and parcel of Marvel’s playbook, and it all goes back to one unplanned moment that changed everything.

Marvel’s Comics Changes All Trace Back To Iron Man

“I Am Iron Man” Was A Bold Change

The truth is that Marvel laid out its stall from the jump. Iron Man’s influence on the superhero genre in general is clear, with the MCU’s unmatched success turning what was once an obscure Marvel hero into one of its most illustrious. Iron Man’s ending, which saw Tony Stark confidently unmask himself to the world, was brazen enough to make it seem as if Iron Man was always a candid hero – but that isn’t the case. In fact, the line was ad-libbed by Robert Downey Jr. and set a new standard that was then actively taken on by Marvel Studios.

Tony Stark was a more serious character in Marvel Comics before RDJ’s take became the archetype for the character in the future.

Marvel’s decision to conclude its debut movie with such a stark contravention of established comic book lore was bold, especially after scoring such a win with its expert casting. Until then, superheroes maintaining a secret identity was one of the biggest superhero tropes, which is why Tony Stark’s iconic closing line was so full of impact for casual moviegoers. It became so iconic, however, that it can be easy to forget just how much this diverted from comic book precedent, and that the MCU has been willing to do so from the very start.

And none of what followed was accidental. As Kevin Feige told Deadline in 2018, Robert Downey Jr’s ad-lib and divergence from the comics gave the studio the confidence to change other stories that followed it:

“That success [of Iron Man ‘s twist ending] inspired us [at Marvel Studios] to go further in the trusting ourselves to find balance of staying true to the comics and the spirit of the comics but not being afraid to adapt and evolve and to change things.”

It is fitting that Robert Downey Jr sits once more at the center of what may be a significant departure from comic book lore. The MCU’s decision to cast the MCU icon as its Doctor Doom has spawned several theories, with the idea that he is playing a Tony Stark variant being chief among them while evoking concerns that Marvel will have to detract at least slightly from Doom’s established comic book lore. Whether this will be the case remains to be seen, but perhaps concerns may be somewhat overblown.

There Are Actually Positives To Marvel Changing Original Stories

The MCU’s Changes Have Worked Out Well (For The Most Part)

Marvel has proved that swinging changes from original stories are generally beneficial. When it comes to Doom, it might be reassuring to reflect on how much the MCU altered Thanos, a villain that remains its most consequential and one of the most beloved. Omitting such paraphernalia from his arsenal as his Thanos-Copter and changing his personality to being a dispassionate and somewhat sympathetic villain from an ordinarily sadistic and power-hungry one made him immensely compelling. The MCU also wisely altered Thanos’ motives away from an obsession with Mistress Death.

The MCU nodded to Thanos “courting death” in his debut scene in the post-credits of The Avengers .

Changing the origins of Ultron, Scarlet Witch, and Quicksilver, were also positive examples of how minor changes to comic book lore can be beneficial as it ties them more closely to the wider narrative. Wanda and Pietro’s connection to the Mind Stone adds more compelling complexity to the Avengers’ relationship with the Infinity Stones, and Wanda’s relationship with Vision in particular. Meanwhile, the creation of Ultron became a cornerstone of Tony Stark’s iconic MCU story, and may still impact Doom’s, once again drawing from the MCU’s wider narrative.

That is not to say, of course, that there haven’t been a few misses. Iron Man 3‘s infamous rug-pull with the Mandarin warranted a swift retcon one year later as the All Hail the King one-shot established that the real Mandarin was entirely removed from Trevor Slattery and Aldrich Killian, though he would tragically never come to blows with his rival, Iron Man. The conspicuous absence of Uncle Ben, meanwhile, remains a sticking point for Spider-Man fans aware of how important the character is to his identity.

Ultimately, however, there is no way of knowing what Marvel intends to do with Doctor Doom until further details about Avengers: Doomsday emerge. The ball may start rolling with The Fantastic Four: First Steps, given Doom is so closely tied to the team in the comics, though RDJ’s involvement in that movie is unconfirmed as yet. There is a lot to be said, however, for the unpredictability of Doom’s future, with the precedent of creative license established in Iron Man ensuring that not even a deep knowledge of the comics can reveal exactly what’s to come.