Dunesday: The Ultimate Avengers: Doomsday And Dune 3 Guide For December 18, 2026

One of the biggest cinematic showdowns in years (if not ever) is on the horizon. What showdown is that, exactly? It's coming our way in December and features two gigantic movie franchises going toe-to-toe on the big screen. Get ready for Dunesday.

While the term may not have taken off in the mainstream quite yet, it's the unofficial name for the showdown between "Avengers: Doomsday" and "Dune: Part Three" going down later this year. Marvel Studios has released four "Avengers: Doomsday" trailers already, and that's just the tip of the iceberg. Meanwhile, Warner Bros.' third cinematic installment in the "Dune" universe is positioned as an "art meets large-scale entertainment" blockbuster the likes of which we don't see all that often.

It's playing on the whole Barbenheimer phenomenon, which saw both "Barbie" and "Oppenheimner" released on the same day, both of which became some of the biggest surprise hits of 2023 at the box office. Will history repeat itself again with this double bill? Or will one of these blockbusters get the short end of the stick? There's a lot to think about, some of which will impact fans of both franchises.

With that, we're here to provide your one-stop guide for Dunesday so you, dear reader, can be ready when the pop cultural event arrives on December 18, 2026.

Dunesday, very simply, is the unofficial term that refers to the forthcoming theatrical showdown between "Avengers: Doomsday" and "Dune: Part Three." Both movies are hitting theaters on the same day, December 18, to be exact. Both are huge cinematic events, and both are going to be of major interest to many moviegoers. But how did the term come about in the first place? We have the biggest stars from these blockbusters to thank.

In January, during a screening of "Marty Supreme," which is nominated for Best Picture at the 2026 Oscars, Robert Downey Jr. appeared on stage alongside the movie's star Timothée Chalamet. During the chat, Downey made a joke about the fact that "Avengers: Doomsday" and "Dune: Part Three" are both scheduled to open on the same day. He even gave the match-up a name (via Deadline). Here's what he had to say:

"We both have films opening on December 18, and we decided to coin it ... We're thinking Dunesday."

"We'll see if we're still friends by then," Downey quipped to conclude the whole thing. Though it was a light-hearted joke, playing along with Chalamet, there is a great deal at stake for both of these movies and their respective studios, namely Disney and Warner Bros. All the same, it was an opportunity for RDJ and Chalamet to acknowledge the situation and have some fun with it.

When "Barbie" and "Oppenheimer" arrived in July 2023, it was a huge deal. Barbenheimer was a bombshell box office success, with both movies delivering more than $240 million worth of business in the U.S. alone on opening weekend. In the wake of that success, the internet tried to create other similar matchups with commercial upside. There was Saw Patrol later that year, when "Saw X" and "Paw Patrol: The Mighty Movie" duked it out.

We also had Garfuriosa in 2024, which was the opposite of Barbenheimer at the box office, as "Furiosa: A Mad Max Saga" bombed and "The Garfield Movie" was at best a modest success. The point is, no other match-up we've had since matched the high heights of that fateful weekend in 2023. Dunesday is the first one that not only feels like it could match those heights, but might even surpass them.

"The Avengers" movies are all among the highest-grossing movies of all time. "Avengers: Endgame" was the biggest movie ever, albeit briefly. Meanwhile, "Dune" was still a big success despite the pandemic, while "Dune: Part Two" became a breakout sequel, making a whole lot more globally. Both of the "Dune" movies were also huge critical darlings. That's what makes this match-up so compelling. There's a huge upside in both cases and a built-in global audience for both. Even going head-to-head, it's easy to see both coming out a winner.

Any time an "Avengers" movie is coming out, it's a big deal. We haven't had one since 2019, which makes "Avengers: Doomsday" an even bigger deal. But it's also important to note that the Marvel Cinematic Universe has been an up-and-down ride during the Multiverse Saga, encapsulating everything in the franchise from 2020 and beyond. As a result, Disney and Marvel Studios need this movie to work.

Marvel's box office in 2025 proved that the MCU has fallen from grace. "Captain America: Brave New World," "Thunderbolts*," and "The Fantastic Four: First Steps" fell short of expectations. While "Brave New World" had a mixed reception, both "Thunderbolts" and "Fantastic Four" earned positive reviews, making those results all the more disappointing. Looking more broadly, seven MCU movies have failed to cross the $500 million mark during the Multiverse Saga. That's a benchmark that used to be considered a bare minimum for this franchise. To say that the pressure is on would be an understatement.

"Doomsday" brings back directors Joe and Anthony Russo, who helmed both "Infinity War" and "Endgame." It's also got the hook of former "Iron Man" star Robert Downey Jr. as the villain Doctor Doom. Not to mention the fact that it's setting up next year's "Avengers: Secret Wars," poised to be an even bigger event.

This is a crucial movie to the future of the MCU, and it's probably costing Disney a fortune just in cast salaries alone. It's got a great shot at being the biggest movie of the year when all's said and done. It's got that "saving the best for last" feel to it, since it's coming out in December. If the Russo brothers deliver the goods once again, it's going to be tough to top.

Despite going up against Earth's Mightiest Heroes, we can't discount "Dune: Part Three." Adapting author Frank Herbert's third novel in the series, namely "Dune Messiah," this one has a lot of intrigue for several reasons. For one, there will be a pretty major time jump. While that presents a challenge since they're keeping Timothée Chalamet as Paul Atreides, given that he's aged up quite a bit in the novel, it's also an avenue to let it be something different.

"Dune: Part Three" will also be director Denis Villeneuve's final entry in the series. Villeneuve has guided this series well, and that's not to say Warner Bros. won't continue the franchise; we just will likely have a different director. That being the case, audiences will likely want to see what Villeneuve has to say on his way out the door. It's the finale of one of the most beloved franchises to emerge on the big screen in the 2020s. It's a big deal.

It's also important to point out that "Dune: Part Two" made well over $700 million at the box office, whereas the first one barely got past $400 million in its original run (albeit hampered by COVID-19). The audience has increased, and Timothee Chalamet's star power has only grown. There's every reason to believe the third installment will be the biggest yet, especially if Warner Bros. can lean on all of these points effectively in the marketing.

On paper, "Avengers: Doomsday" has the edge, but that doesn't mean that "Dune" is going to have to take a back seat.

One thing that happens at the box office a lot of the time is we discuss it in terms of winners or losers. In reality, everything is relative. A given weekend can have a variety of winners and losers; it's bigger than which movie comes out on top. A hugely expensive movie could take number one and still be a flop relative to its budget, while a movie could scarcely crack the top five and be a huge hit because it was made on the cheap.

All of this to say, when we think about Dunesday, it's one of those situations where everyone can and likely will win. Disney will get a surefire $1 billion hit with "Avengers: Doomsday." Warner Bros. damn well could have a $1 billion hit in "Dune: Part Three" if all goes well. Theaters are in desperate need of hits, and both of these movies are likely going to be big hits. It's going to make for a gigantic weekend.

"Dune: Part Three does have one big advantage, as Warner Bros. has secured IMAX screens for that weekend. "Doomsday" (and "Spider-Man: Brand New Day") have their IMAX releases in question right now. While that's a separate, more complicated issue, it's one of the only downsides of both movies releasing the same day. For anyone planning to see both movies on the opening weekend, that will be a factor.

Rest assured, there will be lots and lots of people trying to see both movies asap. With that in mind, viewers should be prepared for crowded theaters, grabbing tickets ahead of time, and planning ahead. This won't be an average weekend at the movies.

"Avengers: Doomsday" and "Dune: Part Three" both hit theaters on December 18, 2026.