What Is ‘Dunesday’? Hollywood Gears Up for a New ‘Barbenheimer’ Between Marvel and Dune

Share:

During a Q&A for the Golden Globe-winning Marty Supreme in Los Angeles on Wednesday, a lighthearted exchange between stars ended up igniting a broader conversation across the film world. Robert Downey Jr. pointed out a key detail: Avengers: Doomsday and Dune: Part Three are both set to premiere on the same day—December 18, 2026. Far from being an awkward coincidence, the moment sparked a nickname that’s already gaining traction on social media.

“We both have films opening on December 18th, and we decided to coin a name for it. We’re thinking ‘Dunesday,’” Downey and Timothée Chalamet said while referring to the unusual release-date clash. The term is a clear nod to the “Barbenheimer” phenomenon, which in 2023 saw Barbie and Oppenheimer release on the same day, sparking an organic wave of memes, double-feature moviegoing, and online discourse that turned an unlikely box-office clash into a cultural event.

Robert Downey Jr. and Timothée Chalamet on ‘AVENGERS: DOOMSDAY’ and ‘DUNE: PART 3’ releasing on the same day:

“We both have films opening on December 18th, and we decided to coin a name for it. We’re thinking ‘DUNESDAY.’”

(via @timotheenation)

pic.twitter.com/FtnyR3c2Kz

— Avengers Updates (@AvengersUpdated) January 15, 2026

The audience reaction was immediate. Fans of Marvel and the Dune universe embraced “Dunesday” with enthusiasm, fueling memes, likes, and debates that have only amplified anticipation. For many, the date promises a double celebration of blockbuster cinema, with two massive franchises competing for attention—and box-office dominance—during the holiday season.

However, as always on social media, skepticism followed. Some doubt that the hype of “Barbenheimer” can be replicated, or at least not in the same way.

Chalamet, “One of the Greats,” According to Downey

Downey also used the moment to publicly praise Chalamet, calling him “one of the greats” of his generation and highlighting the mutual respect that exists despite the direct competition. And he’s not wrong: the actor is one of the top contenders to take home the Oscar in 2026. That camaraderie is mirrored by the stance of the studios involved: Marvel and Warner Bros./Legendary have chosen to stick with their release dates, embracing the clash as a friendly rivalry.

Whether “Dunesday” will evolve into a cultural phenomenon on par with its predecessor or remain a clever marketing curiosity won’t be known until 2026. For now, Hollywood has a new key date circled on the calendar.