David Harbour Praises Robert Downey Jr. Ahead of Avengers: Doomsday

David Harbour’s next stretch of work puts him in two very different but potentially complementary lanes: a massive Marvel ensemble in Avengers: Doomsday and an as-yet-untitled project that reunites him with Millie Bobby Brown. Speaking during the Emmys, Harbour touched on both projects, offering a glimpse of the atmosphere around the Marvel production while carefully keeping the Brown collaboration’s actual premise under wraps.

The immediate headline for superhero fans is that Harbour will once again play Alexei Shostakov, better known as Red Guardian, in Avengers: Doomsday. The film is currently set to reach theaters on Dec. 18. Harbour has already played the character in Black Widow and Thunderbolts*, two films that established the loud, emotionally blunt, frequently hilarious Soviet super-soldier as a distinct presence in Marvel’s expanding cast.

This time, however, Red Guardian is entering a project whose scale naturally invites speculation. Harbour described the feeling of working on a production where beloved Marvel figures and big-screen-style moments are all sharing the same physical space. For someone who has spent years watching the franchise as an audience member as well as participating in it, he framed that transition from fan seat to set as an especially strange and exciting experience.

Harbour on working with Robert Downey Jr.

Harbour’s comments about Robert Downey Jr. were notably enthusiastic. He called Downey Jr. a creative powerhouse and emphasized his unpredictability, presenting that quality as a major pleasure of the collaboration rather than a mystery to be solved. In an ensemble built around outsized characters, that kind of performer energy can be a useful indicator of the tone on set, even if it tells audiences virtually nothing concrete about the story.

It is important not to read a plot reveal into a warm cast comment. Harbour did not provide character details, disclose scenes, or explain the nature of his work with Downey Jr. Still, his remarks do underline one of the most inherently exciting elements of a crossover-scale Marvel movie: actors who have long been associated with different corners of the screen universe getting an opportunity to interact.

For Harbour specifically, the return carries some extra texture. Red Guardian has largely been defined by contradiction. He is boastful yet needy, absurdly confident yet obviously vulnerable, and often a walking disruption to anyone attempting a serious conversation. That mix gave Harbour room to approach comic-book spectacle through character comedy, family tension, physicality, and a fair amount of shouting. In a film titled Avengers: Doomsday, the question is not merely whether the character can produce another memorable entrance. It is how that unruly energy functions when the stakes and the gathering of personalities grow larger.

Why the fan perspective matters

Harbour has been clear that he remains a fan of the movies in which he appears. He pointed to the thrill of seeing the sort of event moments he once cheered for from the audience now unfold around him as an actor. That perspective is relatable because it recognizes the peculiar alchemy behind long-running franchise storytelling. Viewers arrive with years of associations, favorite scenes, and memories of earlier theatrical moments. Performers can carry those same associations into the work, but they must also keep their focus on the immediate scene in front of them.

There is a difference between nostalgia and useful creative investment. The former can simply repeat what has already worked; the latter can help actors understand why a meeting, a team-up, or a confrontation might matter to viewers. Harbour’s comments suggest he appreciates the rare scale of those encounters without pretending to offer a roadmap for them.

That restraint is welcome. Major superhero productions generate a constant swirl of assumptions, casting theories, purported leaks, and title-based predictions. At present, the confirmed information in Harbour’s remarks is straightforward: Red Guardian is back, Avengers: Doomsday is headed for theaters on Dec. 18, and Harbour has enjoyed working closely with Downey Jr. The rest remains material for audience imagination rather than established fact.

A new Harbour and Millie Bobby Brown father-daughter story

Outside the Marvel machine, Harbour also previewed a future reunion with Millie Bobby Brown. The pair’s previous work together made their father-daughter dynamic central to the emotional foundation of Stranger Things. Their upcoming project is not being publicly identified by title, and its plot has not been revealed. Harbour was direct about that boundary: details will come later, not now.

What he was willing to say is revealing on its own. The new project will again draw on a father-daughter relationship, but it intends to explore a different stage of life. Brown is now in her 20s, and Harbour described an interest in examining what it means to parent—or father—someone navigating that period of adulthood. That offers a meaningful shift from the teenage-focused family material audiences associate with their earlier collaboration.

It would be easy to reduce this to a familiar reunion headline, but the stated creative angle makes it more specific than that. A father-daughter relationship is not static simply because its participants know and love one another. The expectations, boundaries, and pressures can change radically as a child becomes an adult. Harbour’s description points toward family as a core concern, while also promising an action-and-entertainment engine strong enough to propel the project forward.

That combination is still broad, and it should stay broad until the team shares more. There is no disclosed setting, supporting cast, release window, platform, or character information. There is also no reason to assume it resembles Stranger Things beyond the shared pairing and the broad relational dynamic. The sensible takeaway is that Harbour and Brown are deliberately returning to a creative connection that audiences already recognize, but they plan to use it to investigate a new life chapter.

Jack Thorne is writing the untitled project

One firm creative detail is that Jack Thorne is writing the project. Harbour spoke warmly about the writer and his excitement to begin work. In practical terms, that confirms a key person behind the new series or film while leaving its larger shape undisclosed.

For now, the project’s appeal rests on its premise rather than its packaging: Harbour and Brown playing into a family bond they have already made convincing, with the story turning toward the complications of adulthood and combining those issues with action-driven entertainment. It is a clear enough foundation to be intriguing, even without a title or a synopsis.

The entertainment world’s awards calendar has also provided a timely reminder that Harbour’s interests extend well beyond franchise work. On Sept. 6, he earned his first Emmy at the Creative Arts Emmys, winning Outstanding Supporting Actor in a Limited or Anthology Series for Floyd Smernitch in DTF St. Louis. The recognition arrives at a moment when his upcoming slate includes both one of cinema’s biggest shared-universe projects and a more intimate-sounding reunion built around family.

For a wider look at the 2026 Emmys’ pop-culture moments, see Zendaya’s crystal Prada Emmys look and its late-’90s beauty connection.

What is confirmed, and what remains unknown

In an era when every franchise appearance can turn into a dozen speculative headlines, separating confirmed information from the open questions is useful. Here is the current picture:

Harbour will reprise Alexei Shostakov/Red Guardian in Avengers: Doomsday.
Avengers: Doomsday is set for a Dec. 18 theatrical release.
Harbour has worked closely with Robert Downey Jr. and praised his creative approach.
Harbour and Millie Bobby Brown are reuniting for an untitled project built around a father-daughter dynamic.
That project will consider adulthood and family, include action and entertainment elements, and is being written by Jack Thorne.
Its title, plot, release plan, and further casting have not been disclosed.

That is already plenty for fans of Harbour’s work to track. Red Guardian’s return places him back in the center of superhero spectacle, while the Brown reunion suggests a different kind of character-driven collaboration is on the horizon. The connective tissue is Harbour himself: an actor who can speak with genuine fan enthusiasm about a giant Marvel set one moment and, the next, focus on the evolving emotional terms of a father-daughter relationship.