Avengers: Doomsday Theory: Could Doctor Doom Be a Tony Stark Variant? The Endgame Connection Explained

A surprising theory may have found a connection between Avengers: Endgame Extras and Avengers: Doomsday—and it could involve one of the biggest characters in Marvel history.

According to the Russo Brothers, Avengers: Endgame Extras will be important for understanding the story of Avengers: Doomsday. That revelation has naturally left Marvel fans wondering exactly what viewers are supposed to notice.

One fan theory offers an especially intriguing possibility: Doctor Doom could actually be a variant of Tony Stark.

The theory is unconfirmed, but if it turns out to be true, it could potentially explain several major mysteries surrounding Avengers: Doomsday, including the return of Robert Downey Jr. and the unexpected involvement of Steve Rogers.

The Theory Connecting Endgame Extras to Avengers: Doomsday

The theory comes from Marvel Mania's X-Men theory, which suggests that Doctor Doom could be the reason Doctor Strange saw only one successful outcome for the Avengers during Avengers: Endgame.

The theory proposes that Doom may be an alternate version of Tony Stark—one who survived the events of Endgame rather than making the ultimate sacrifice.

In this possible reality, Stark could have found another way to defeat Thanos without dying. However, surviving might have eventually led him down a very different path.

According to the theory:

“Doctor Doom is the reason Doctor Strange has only seen one universe where the Avengers won.”

The idea is that Doctor Strange may have seen a future in which Tony Stark survived but eventually became Doctor Doom. If so, Strange could have deliberately guided events toward the timeline where Stark sacrificed himself, preventing that alternate future from happening.

It is a huge hypothetical twist, but it creates an interesting connection between Tony Stark's fate and the arrival of Doctor Doom.

Could Doctor Doom Really Be a Tony Stark Variant?

The theory becomes even more interesting when Robert Downey Jr. enters the picture.

Downey Jr. played Tony Stark throughout more than a decade of the MCU before the character's sacrifice in Avengers: Endgame. His casting as Doctor Doom therefore immediately created questions about why Marvel chose an actor so closely associated with Iron Man.

If Doom were indeed a Tony Stark variant, the casting would suddenly have a very different meaning.

Rather than simply bringing back a familiar MCU star in a completely unrelated role, Marvel could potentially be using Downey Jr.'s established connection with Tony Stark as part of the story itself.

However, the supplied theory remains just that—a fan theory. Nothing in the information provided confirms that Doctor Doom is actually a variant of Tony Stark.

What Does Doctor Strange Have to Do With It?

The theory also puts a new spin on Doctor Strange's actions in Avengers: Endgame.

Strange famously examined countless possible outcomes before identifying the single scenario in which the Avengers could defeat Thanos.

The fan theory suggests that the successful outcome may have involved more than simply defeating Thanos.

It could also have been about preventing a much bigger threat from emerging later.

If one alternate universe allowed Tony Stark to survive and eventually become Doctor Doom, Strange's decision could have been about preserving a reality where Stark dies as a hero rather than allowing a potentially dangerous version of him to continue living.

That interpretation would give Tony's sacrifice an additional layer of significance.

It could also potentially connect to the rumored Doomsday and Secret Wars storyline involving Doctor Strange and Doom, although the supplied information does not confirm how those elements will ultimately fit together.

Why Is Steve Rogers Back?

The theory also attempts to explain another mystery surrounding Avengers: Doomsday: the return of Steve Rogers, played by Chris Evans.

At the conclusion of Avengers: Endgame, Steve traveled back in time to return the Infinity Stones. Instead of immediately returning to the present, he chose to live his life with Peggy Carter.

He eventually appeared as an elderly man and passed the Captain America shield to Sam Wilson.

That made his reported return to Avengers: Doomsday particularly puzzling.

The fan theory proposes that the Steve Rogers appearing in Doomsday could potentially come from the same alternate universe in which Tony Stark survived.

In that reality, the events of Endgame may have unfolded differently. Tony could have survived the final battle, while Steve might never have truly retired.

The theory points to Steve's reported appearance as another possible clue, suggesting that his near-Endgame appearance could indicate a connection to an alternate reality.

Again, however, this is speculation rather than confirmed information.

Why This Matters

If the theory is correct, it could give Avengers: Doomsday a deeply personal connection to the MCU's original Avengers era.

Tony Stark's sacrifice was one of the defining moments of Avengers: Endgame. Turning an alternate version of that character into Doctor Doom would create a striking contrast between Tony Stark, the hero who sacrificed himself, and a version of Stark who survived and potentially became Marvel's villain.

It could also explain why Robert Downey Jr. was chosen for Doctor Doom while giving Doctor Strange's actions in Endgame an entirely new meaning.

At the same time, the theory attempts to connect two other major pieces of the puzzle: Steve Rogers' return and the multiverse storyline surrounding Avengers: Doomsday.

A Theory That Still Needs to Be Proven

There is an important catch.

The theory does not appear to match the plot rumors surrounding Avengers: Doomsday mentioned in the supplied information. That makes it difficult to treat the Tony Stark-Doom connection as anything more than an interesting possibility at this stage.

Marvel has also kept major details about Doomsday under wraps, leaving plenty of room for fan speculation.

For now, the idea that Doctor Doom could be a Tony Stark variant remains unconfirmed. But the fact that it could potentially explain Robert Downey Jr.'s casting, Doctor Strange's Endgame decision and Steve Rogers' return makes it one of the more intriguing theories surrounding the upcoming Avengers movie.

When Will Avengers: Endgame Extras and Avengers: Doomsday Arrive?

According to the supplied information, Avengers: Endgame Extras is scheduled to arrive on September 24, while Avengers: Doomsday is set to debut on December 16.

If the Russo Brothers are correct that Endgame Extras will be central to understanding Doomsday, viewers may discover important clues before the new Avengers story reaches theaters.

Whether those clues point toward Tony Stark, Doctor Doom, Steve Rogers or an entirely different multiverse connection remains to be seen.

For now, the biggest question is simple: Did Doctor Strange save the Avengers in Endgame—or did he also prevent Tony Stark from becoming Doctor Doom?