Back for Avengers: Doomsday — Robert Downey Jr. shares why he’s returning to the MCU

Here we go then: Robert Downey Jr., the man who basically kickstarted the MCU craze as Tony Stark, is officially coming back — but not as Iron Man. Nope, in a bit of Marvel casting jiu-jitsu, he’s now set to play the villain for Avengers: Doomsday. He’s swapping out the metal suit for a megalomaniac cape, taking on the role of Doctor Doom. Yes, really.

Why Downey's Back (And Why as Doom?)

So after capping off over a decade in the franchise with Iron Man’s dramatic demise in Avengers: Endgame, you’d think Downey Jr. was done for good — but Marvel loves a resurrection in some form, doesn’t it?

Downey Jr. popped up on the official MCU podcast dedicated to hyping up Doomsday, and here’s how he explained what brought him home to Marvel, this time on the other side of the moral divide:

On the Countdown to Avengers: Doomsday Official Podcast, Downey Jr. dropped this on why he returned:

What brought me back was the opportunity to redefine the genre of superhero movies, so that’s a tall order. You know, Mr. Feige, you know the group, we love a challenge, and we figured, 'Wow, let’s mix it up and see if we can get ourselves excited, because if we’re excited, the audience will soon follow.'

So, in classic Downey Jr. fashion, he’s not just chasing a paycheque – apparently he wants to shake up the whole superhero movie thing. Good luck with that, Rob, it’s getting a bit formulaic out there these days.

The Overstuffed Cast List

This is Marvel, so they’re not content with just a villainous Downey. Avengers: Doomsday has a line-up that looks like someone’s shoved every A-lister into a single IMAX screen. It’s essentially Avengers, Wakanda, New Avengers, Fantastic Four, and the X-Men having a massive scrap with Doctor Doom.

• Chris Evans (presumably back as Captain America in some form)
• Chris Hemsworth (Thor, obviously)
• Paul Rudd, Sebastian Stan, Danny Ramirez, Anthony Mackie – the usual Avenger suspects
• Tom Hiddleston shows up as Loki, because of course he does
• Benedict Cumberbatch, Jeremy Renner also along for the ride
• The new Fantastic Four – Pedro Pascal, Vanessa Kirby, Ebon Moss-Bachrach, Joseph Quinn (they're all set to return)
• From Black Panther: Letitia Wright, Winston Duke, Mabel Cadena, Tenoch Huerta Mejía
• New Avengers crew: Florence Pugh, Wyatt Russell, David Harbour, Lewis Pullman, Hannah John-Kamen
• And here’s a nostalgia bomb: classic X-Men including Ian McKellen, Patrick Stewart, James Marsden, Kelsey Grammer, Alan Cumming and Rebecca Romijn

It’s basically everyone bar your nan, and Marvel might still be casting as we speak.

Avengers: Doomsday hits cinemas 18 December 2026.