The Marvel Cinematic Universe is poised to connect Doctor Doom and Iron Man in Avengers: Doomsday and Avengers: Secret Wars, and while the exact explanation has not come, a Marvel theory suggests it was already revealed years ago. Theories have been running wild for nearly two years about how Victor Von Doom and Tony Stark may be tied, ever since Robert Downey Jr.’s casting was announced at San Diego Comic-Con 2024.
The biggest assumption for why Marvel recast RDJ with this villain role has been that they are variants of each other. As the big bad of the Multiverse Saga’s conclusion, linking Iron Man and Doctor Doom in this way would make sense for the larger universe and explain why Downey specifically had to be the one to play Victor. However, a non-multiverse-specific explanation appears to be coming.
The Russo brothers have confirmed that the next two Avengers movies will explain how Doctor Doom and Iron Man are connected. Joe said, “It will all make sense when you watch the movies.” Anthony hinted at the connection reshaping the very fabric of Doom’s conception, saying, “It’s a brand new character that you can’t even guess at.”
From “I Am Iron Man” to “I Am Inevitable” · Eight Questions How Well Do You Know the MCU? “Whatever it takes.”
🤖Phase OneRDJ & the founders, 2008
🛡The AvengersWhedon’s team, 2012
💎Infinity SagaThanos & the stones
⚡EndgameWhatever it takes, 2019
🌏MultiversePhase 4–6, 2021–
01
Iron Man (2008) is, in retrospect, the most consequential casting decision in modern blockbuster history — but at the time Marvel Studios and parent company Paramount were openly hostile to director Jon Favreau’s push for the lead actor he eventually got. Favreau later said he had to fight “tooth and nail” and the actor had to do a paid screen test, a screen-test deal almost unheard of for an A-lister. What was the executive objection to him?
✓ Correct! Robert Downey Jr. had been arrested multiple times between 1996 and 2001 on drug and weapons charges, served roughly a year in California state prison (1999–2000), and was fired from Ally McBeal in 2001 after relapsing. By 2007 he’d been clean for several years, but Marvel/Paramount considered him essentially uninsurable for a $140 million tent-pole. Favreau pushed for him over studio favourites Tom Cruise (who’d had Iron Man development at Fox years earlier) and Sam Rockwell (who’d later play Justin Hammer in Iron Man 2 as a consolation). RDJ took a reported $500,000 base salary — less than Terrence Howard, whose role he then permanently overshadowed.
✗ Wrong. The answer is his arrest history. RDJ had drug-related arrests from 1996–2001, served prison time in 1999–2000, and was fired from Ally McBeal in 2001 — which made him uninsurable in studio terms even though he’d been sober for several years by 2007. Favreau fought for him over Tom Cruise and Sam Rockwell, and RDJ took a reported $500,000 base salary — less than co-star Terrence Howard.
02
The Avengers (2012) — the film that proved the shared-universe model could work, grossed $1.52 billion, and ended Phase One with Loki, Thanos’s mid-credits reveal, and the “swarm shot” of the team rotating in Manhattan — was written and directed by a TV showrunner best known at the time for Buffy the Vampire Slayer and Firefly. Name him.
✓ Correct! Joss Whedon. Marvel hired him in mid-2010 partly on the basis of his uncredited script rewrites and his comfort writing ensemble team dynamics from Buffy/Angel/Firefly. He directed The Avengers (2012) and the follow-up Age of Ultron (2015), then exited the MCU and Marvel handed the next two Avengers films to the Russo brothers. The three other directors named all really did make Phase One films: Favreau directed Iron Man (2008) and Iron Man 2 (2010), Branagh directed Thor (2011), and Joe Johnston directed Captain America: The First Avenger (2011) — which is why this question separates Phase One trivia from Avengers-specific trivia.
✗ Wrong. The answer is Joss Whedon — hired largely on the strength of Buffy, Firefly, and uncredited Hollywood script work. The three wrong options are deliberately all real Phase One MCU directors: Favreau did Iron Man 1 & 2, Branagh did Thor (2011), and Joe Johnston did The First Avenger (2011). Whedon directed Avengers (2012) and Age of Ultron (2015) before exiting the MCU.
03
Marvel co-architect Stan Lee (1922–2018) appeared in every theatrical MCU film from Iron Man (2008) onward, even shooting cameos in advance to outlast him. He died on November 12, 2018. In which film does his final filmed MCU cameo appear — as the long-haired young driver of a 1970 car bearing the bumper sticker “NUFF SAID”?
✓ Correct! Avengers: Endgame (April 2019). Lee appears digitally de-aged behind the wheel of a 1970 Chevy at the New Jersey army base where Tony Stark and Steve Rogers travel back to retrieve the Tesseract; he shouts “hey man, make love, not war!” The cameo was filmed before Lee’s death and confirmed by the Russos as his final filmed MCU appearance, although the next-released film, Spider-Man: Far From Home (July 2019), became the first MCU film with no Stan Lee cameo at all. Captain Marvel (March 2019) has him reading the script for Mallrats on the L.A. train and was the first posthumously-released cameo, but Endgame was the last one he actually shot.
✗ Wrong. The answer is Avengers: Endgame — the de-aged hippie-era driver in the 1970 New Jersey time-heist scene. Captain Marvel (March 2019) was the first cameo to release posthumously, but Endgame (April 2019) was the last one Lee actually filmed. Spider-Man: Far From Home (July 2019) became the first MCU film with no Stan Lee cameo at all.
04
Across Phase One through Three, each Infinity Stone is hidden inside a distinctive container before being claimed for Thanos’s Gauntlet. The blue Space Stone is housed inside a glowing cube that originates with the Asgardians, is recovered by Howard Stark from the wreckage of the Red Skull’s plane, is taken to Asgard by Loki in 2012, and is finally retrieved by Hulk on Sakaar before falling to Thanos. What is that container called?
✓ Correct! The Tesseract — the blue cube that houses the Space Stone — first appears in Captain America: The First Avenger (2011), powers the portal Loki opens over Manhattan in The Avengers (2012), and is destroyed by Thanos in Infinity War (2018) when he crushes it to claim the stone inside. The wrong options are all real Infinity Stone containers from the MCU: the Aether (red liquid form) houses the Reality Stone in Thor: The Dark World, the Orb houses the Power Stone in Guardians of the Galaxy, and the Eye of Agamotto houses the Time Stone in Doctor Strange. So all four answers refer to genuine stone containers — only the Tesseract holds Space.
✗ Wrong. The answer is the Tesseract. The trap is that all four options are real Infinity Stone containers: the Aether holds Reality (Thor: The Dark World), the Orb holds Power (Guardians of the Galaxy), and the Eye of Agamotto holds Time (Doctor Strange). Space — the blue stone shown in Cap’s 1942 plane wreckage and Loki’s 2012 invasion — is the Tesseract.
05
In Avengers: Infinity War (2018), the Soul Stone is hidden on Vormir and guarded by a Stonekeeper — revealed to be a cursed Red Skull. To claim it, the seeker must sacrifice the person they love most by throwing them from a cliff. Thanos arrives on Vormir with one adopted daughter, weeps, and pushes her over the edge. Which character does Thanos sacrifice to obtain the Soul Stone?
✓ Correct! Gamora (Zoe Saldaña). Thanos forces her to lead him to Vormir because Nebula has earlier revealed under torture that Gamora knew the Soul Stone’s location all along. The scene is the emotional pivot of Infinity War: it confirms that Thanos really does love Gamora, which means the sacrifice qualifies. In Endgame (2019), a 2014 version of Gamora returns through time travel with her father — meaning Gamora-of-Infinity-War remains dead at the end of the saga, while a different Gamora wanders the cosmos in Guardians of the Galaxy Vol. 3. Nebula is alive throughout Infinity War; Mantis survives Vormir entirely; Proxima Midnight is one of Thanos’s Black Order children, killed in the Battle of Wakanda.
✗ Wrong. The answer is Gamora. Nebula is alive throughout Infinity War (she’s the one whose torture reveals Gamora knew where the stone was hidden). Mantis isn’t on Vormir. Proxima Midnight is Thanos’s adopted daughter via the Black Order, not via Zen-Whoberi, and is killed during the Battle of Wakanda by Scarlet Witch. Thanos sacrifices Gamora — the only adopted daughter he genuinely loves.
06
In Avengers: Endgame (2019), Steve Rogers travels back in time to return the Infinity Stones, then chooses to remain in the past and live out a life with Peggy Carter. He returns to the present as an old man, sits on a bench by the lake at the Avengers compound, and hands his vibranium shield to a younger Avenger as the symbolic transfer of the Captain America identity. To whom does Steve give the shield?
✓ Correct! Sam Wilson (Anthony Mackie) — the Falcon. The choice deliberately bypasses Bucky, the original comics successor, because the Russos and screenwriters Markus & McFeely wanted the moment to read as a deliberate, racially-charged passing of an American icon rather than the obvious comics-canon handoff. The thread is then picked up directly in The Falcon and the Winter Soldier (Disney+, 2021), in which Sam initially gives the shield to the Smithsonian, sees the government install John Walker as a replacement Cap, and ultimately takes the mantle himself — setting up Captain America: Brave New World (2025) with Mackie as the franchise’s new lead.
✗ Wrong. The answer is Sam Wilson, the Falcon. In the comics Bucky is the classic Cap successor, but the Russos and screenwriters Markus and McFeely deliberately picked Sam instead — a choice the entire Falcon and the Winter Soldier series (Disney+, 2021) then unpacks before Mackie carries it into Captain America: Brave New World (2025).
07
After Endgame, Marvel Studios’ Phase Four launched the MCU on Disney+ with a sitcom-pastiche limited series in which Wanda Maximoff and a resurrected Vision live inside a reality-warping suburban hex. Each episode parodied a different era of US TV sitcom — The Dick Van Dyke Show, Bewitched, Family Ties, Modern Family. The show premiered January 15, 2021 and ran nine episodes. Which series was it — the first MCU project on Disney+?
✓ Correct! WandaVision (January 15 – March 5, 2021), created by Jac Schaeffer and directed by Matt Shakman. It launched Phase Four, earned 23 Emmy nominations, and effectively rebooted Wanda Maximoff as the Scarlet Witch ahead of Doctor Strange in the Multiverse of Madness (2022). The Falcon and the Winter Soldier followed it in March 2021 — not first — and Loki landed in June 2021. Hawkeye is the 2021 Christmas series with Jeremy Renner and Hailee Steinfeld. The original launch order was WandaVision → FATWS → Loki → What If…? → Hawkeye, and WandaVision’s sitcom format remains the boldest swing of the Disney+ era.
✗ Wrong. The answer is WandaVision (January 15, 2021), the first MCU show on Disney+ and the launchpad for Phase Four. The Falcon and the Winter Soldier came in March 2021, Loki in June 2021, and Hawkeye in late 2021. The sitcom-pastiche structure — Dick Van Dyke through Modern Family — is unique to WandaVision.
08
At the closing panel of San Diego Comic-Con on July 27, 2024, Marvel Studios president Kevin Feige brought the Russo brothers back on stage to announce a new title for the next Avengers film — previously labelled “The Kang Dynasty” before Jonathan Majors’s December 2023 conviction forced a pivot — and then unmasked a cast of actors wearing green hoods. The final hood came off Robert Downey Jr. RDJ is returning to the MCU, but not as Tony Stark. As whom?
✓ Correct! Doctor Doom — Victor von Doom, the Latverian dictator and Reed Richards’s lifelong nemesis, generally considered Marvel’s greatest comics villain. The next Avengers film, originally announced as Avengers: The Kang Dynasty, was retitled Avengers: Doomsday after Jonathan Majors was dropped as Kang following his December 2023 assault conviction. Doomsday is scheduled for May 2026, with Avengers: Secret Wars to follow in May 2027 — both directed by Anthony and Joe Russo, returning to the MCU after Endgame. The in-universe explanation for RDJ playing Doom rather than Stark hinges on the multiverse: Doom is being positioned as a variant of Stark from another timeline.
✗ Wrong. The answer is Doctor Doom. The film was retitled from Avengers: The Kang Dynasty to Avengers: Doomsday (May 2026) after Jonathan Majors was dropped, and the Russos returned to direct. RDJ’s casting as Doom — rather than as Tony Stark — is being explained in-universe via the multiverse: Doom as a Stark variant from another timeline.
The Stones Are Cast · Final Scorecard Your Avengers Standing
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A worthy Avenger — or dusted in the snap?
Doctor Doom being an Iron Man variant (or vice versa) doesn’t really fit this, as it’s the most obvious and popular suggestion. The real reason RDJ was specifically chosen to play Doom could be because Victor and Tony are brothers. The Russos even already explained how this could be in Avengers: Endgame.
MCU Theory: Doctor Doom & Iron Man Are Biological Brothers
Doctor Doom closeup of mask in Avengers: Doomsday
Even if Doom’s mask never comes off in Doomsday, the MCU will have to eventually address why Victor and Tony look alike. We already know Marvel isn’t undoing Tony’s death in Endgame through this reveal. Some have suggested Doom is dreamwalking in Tony’s body, but that feels too complicated and unnecessary. If the variant explanation isn’t being used, a biological one is possible. But rather than Doom being a distant descendant of Tony, how about a sibling?
The MCU revealing that Victor and Tony are brothers solves the creative, practical, in-universe reason for Downey’s casting (ignoring the financial/popularity reasons that also played a factor). Them being biologically related would mean that Marvel needed someone who at least looks similar to Downey, but rather than find another actor who has some resemblance, they just got the MCU’s original star back to do it.
Marvel could always still use the randomness of the multiverse to explain Downey playing both, similar to how Chris Evans has played Johnny Storm and Steve Rogers. Feige even cited Evans’ dual Marvel roles as a precedent for Downey now portraying Doom in a recent interview. But with the Russos teasing there is a deeper reason, the brother explanation becomes more intriguing. Especially when one Avengers: Endgame scene is reconsidered.
Avengers: Endgame Teased How Doctor Doom Could Be Iron Man’s Brother
In the 2019 blockbuster, Tony goes with Steve to Camp Lehigh in 1970 to acquire the Tesseract and more Pym Particles to complete their time heist. They are successful in this mission, but not without detours to seeing important people from their pasts: Peggy Carter for Steve and Howard Stark for Tony. The exchange between father and son is quite memorable, and it may hold the key to Doom being Iron Man’s brother.
When Tony and Howard walk into an elevator, Tony asks his father about the flowers and sauerkraut he’s carrying, to which Howard remarks that his wife is expecting a child. Tony immediately becomes confused and asks his father how far along she is. The moment has always stuck out as a curious reaction for Tony, as he should know his mother, Maria, is pregnant.
Tony says he has a “vaguely exact idea” about when to go to Camp Lehigh and that “I know for a fact they were there, and I know how I know.” If that vague idea was because he knew his dad was working there while his mom was pregnant with him, then why the surprised reaction to Howard saying his wife is expecting?
Theories have previously suggested that Tony’s response hints towards him being adopted by the Starks, with Howard and Maria’s biological child dying as an infant. This would be comic-accurate, teasing the history of Arno Stark. But perhaps Maria isn’t pregnant with Arno or Tony at this point, but rather a son destined to be Victor von Doom, hence Tony’s odd response.
With Downey now back and playing Doom from another reality, there is an opportunity for Marvel to make Victor the brother Tony never knew he had. As for why they never met, that could come down to Victor dying in the womb, during birth, or as a young child. And the pain of that loss could have led Howard and Maria to never talk about it, explaining why Tony never mentioned it either. It will just take retconning the MCU timeline somewhat.
The MCU Will Need To Retcon A Minor Detail To Make Victor & Tony Stark Brothers
Robert Downey Jr. as Tony Stark in Iron Man
The issue here is that Tony is talking to Howard in Endgame on April 7, 1970, less than two months before his canonical MCU birthday, May 29, 1970, which was established in SHIELD’s file on Iron Man from Iron Man 2. The timeline indicates that Maria is pregnant with Tony at that point, but Marvel could change his birthday to add this connection.
Tony’s birthday is not really that important in the grand scheme of the MCU timeline, only really impacting the date that Iron Man 2 takes place (as he celebrates his birthday midway through). And since the original date is only sourced in a minor SHIELD file, most audiences will not even realize if Marvel makes Iron Man’s birth occur much later in 1970 or in another year entirely.
While the MCU could still do the Doctor Doom and Iron Man brothers twist by making them twins (but where only one survives in each universe potentially), this does not account for Tony’s reaction in Endgame‘s 1970 scene. So, if this is what Marvel has planned for connecting its biggest hero and newest villain, a retcon of some magnitude will have to be introduced.
How Doomsday & Secret Wars Can Address Doctor Doom & Iron Man Being Brothers
Doctor Doom stopping Stormbreaker in Avengers: Doomsday
Whether an explanation comes in Doomsday or Secret Wars, these Avengers movies won’t need to spend much time detailing how Doctor Doom and Iron Man can be brothers. The films will certainly provide some understanding about Victor’s backstory. Mentions that his parents were named Howard and Maria would do the trick alone.
The MCU can then go in numerous directions with the rest of the connection. Howard and Maria could raise a family in Latveria instead of America in one reality. They could find another family to adopt Victor in his or every universe. He could also get adopted as a child after they die.
But to ensure audiences didn’t get confused that Doctor Doom is an Iron Man variant, Doomsday and Secret Wars would also have to confirm that Doom’s family tree includes a brother, Tony. This could even be tied to his motivation for destroying the multiverse and creating a new reality, possibly after watching Earth-616’s Iron Man die (which does tie into Doomsday‘s story).
Such a reveal would explain why Marvel needed Downey to play Doctor Doom in Avengers: Doomsday and Secret Wars. Who better to play Iron Man’s secret brother than Downey? Only time will tell whether this theory proves correct, but it will be a remarkable example of the MCU weaving together different movies to support a big reveal if so.
