With Avengers: Doomsday less than four months away, Marvel Studios has started ramping up the hype for its highly anticipated superhero blockbuster. After five drawn-out teaser trailers and a recently released D23 "special look" at Avengers: Doomsday focusing on the destructive power of Doctor Doom, the impending arrival of the next Avengers film is finally starting to feel real.

There's been one major unknown about Doom since Marvel revealed in 2024 that Robert Downey Jr. was returning to the MCU, not as Tony Stark/Iron Man, but as Latverian supervillain Victor Von Doom: How will Avengers: Doomsday going to address the Tony of it all? Is Victor just Tony from an alternate universe? Will the heroes of the MCU acknowledge that, Hey, this scary new bad guy sure looks a lot like Tony Stark? One actor appearing in Doomsday may have provided some answers.

Potential spoilers ahead for Avengers: Doomsday

David Harbour, who plays Alexei Shostakov/Red Guardian in the MCU, recently sat down with Variety to talk about his HBO show DTF St. Louis, and in doing so offered a tantalizing morsel from Doomsday. Asked by Variety to share one of his lines from the next Avengers film out of context, Harbour responded (in Alexei's Russian accent), "You … are Tony Stark."

Whether Harbour is trolling or being honest is unclear. But his response certainly implies that Red Guardian might be the one to address the elephant in the room, acknowledging that the late Tony Stark and Victor Von Doom share a familiar face. Harbour's character would apparently do so in an inversion on the classic "I am Iron Man" reveal. Given that Doom is from an alternate Earth, where the MCU's Fantastic Four hail from, there's a good reason why characters like Reed Richards and Sue Storm wouldn't know who Tony Stark is. But the rest of the mainline MCU Avengers certainly would.

Thus far, we haven't seen Doomsday's version of Doctor Doom without his mask, so it's not clear how Marvel and directors Joe and Anthony Russo are handling the villain's appearance. One would think that if you're going to pay Robert Downey Jr. tens of millions of dollars to appear in your Marvel movie, you'd want to get his face on screen. Maybe not.

If Doom's identity is a surprise to the majority of the MCU's Avengers, that will be a fun, potentially powerful moment in Doomsday — one that Harbour may have just lightly spoiled. Given Marvel's secrecy, it's unlikely Harbour would reveal major spoilers — especially since he's appeared in previous MCU films Black Widow and Thunderbolts* — lest he run afoul of Kevin Feige's rules. We'll see.

Who's starring in Avengers: Doomsday?

In addition to Robert Downey Jr. as Doctor Doom, the next Avengers movie stars returning Marvel actors Chris Hemsworth as Thor, Anthony Mackie as Captain America, Sebastian Stan as the Winter Soldier, Letitia Wright as Shuri, Paul Rudd as Ant-Man, Wyatt Russell as U.S. Agent, Tenoch Huerta Mejía as Namor, Vanessa Kirby as Sue Storm, Pedro Pascal as Mister Fantastic, Joseph Quinn the Human Torch, Ebon Moss-Bachrach as the Thing, Simu Liu as Shang-Chi, Florence Pugh as White Widow, Kelsey Grammer as the Beast, Lewis Pullman as Sentry, Danny Ramirez as Falcon, David Harbour as Red Guardian, Winston Duke as M'Baku, Hannah John-Kamen as Ghost, Tom Hiddleston as Loki, Patrick Stewart as Professor X, Ian McKellen as Magneto, Alan Cumming as Nightcrawler, Rebecca Romijn as Mystique, James Marsden as Cyclops, and Channing Tatum as Gambit.

Avengers: Doomsday lands in movie theaters on Dec. 18. A direct sequel to Doomsday is already in the works with 2027's Avengers: Secret Wars.