'Avengers: Infinity War' Trailer: Marvel Releases First Look at Biggest Superhero Movie Ever -- Watch!

The Avengers unite with the Guardians of the Galaxy in a team-up featuring nearly every Marvel superhero ever, including Robert Downey Jr., Chris Hemsworth, Scarlett Johansson and more!

We're gonna need a bigger Avengers.

The superheroes of the Marvel Cinematic Universe have bested quite a few villains over the last decade, but they'll soon face the biggest bad of them all -- Thanos the Mad Titan (played by Josh Brolin) -- in Avengers: Infinity War. Which means Iron Man will need to assemble every hero he knows -- Thor! Spider-Man! Doctor Strange! Black Panther! -- and the Avengers will finally team up with the Guardians of the Galaxy, which is all previewed in the first official trailer.

Marvel Studios

Directors Anthony and Joe Russo showed they can handle a superhero-heavy movie with 2016's Captain America: Civil War, but the size of the cast and sheer number of heroes in Infinity War is unprecedented: Robert Downey Jr. (Iron Man), Chris Evans (Captain America), Chris Hemsworth (Thor), Scarlett Johansson (Black Widow), Mark Ruffalo (The Hulk), Jeremy Renner (Hawkeye), Elizabeth Olsen (Scarlet Witch), Paul Bettany (Vision), Anthony Mackie (Falcon), Don Cheadle (War Machine), Sebastian Stan (Winter Solider) Paul Rudd (Ant-Man), Benedict Cumberbatch (Doctor Strange), Benedict Wong (Wong), Chadwick Boseman (Black Panther), Danai Gurira (Okoye), Tom Holland (Spider-Man), Chris Pratt (Star-Lord), Zoe Saldana (Gamora), Dave Bautista (Drax), Pom Klementieff (Mantis) and Karen Gillan (Nebula), along with the voices of Bradley Cooper (Rocket Raccoon) and Vin Diesel (Groot). And that's just the MCU players that are confirmed.

Infinity War arrives in theaters on May 4, 2018, marking the 10-year anniversary of Iron Man, the movie that started it all. Marvel hyped the trailer's release on Tuesday with a fan-centric retrospective, teasing: "Everything You Know, Everything You've Experienced, Everything You've Imagined, It Has All Been Leading to This Moment."

Infinity War will be followed -- after Ant-Man and the Wasp in 2018 and Captain Marvel in 2019 -- by Avengers 4, which is currently filming and will open in 2019. Marvel Studios' Kevin Feige told Vanity Fair that Avengers 4 will include "things you’ve never seen in superhero films: a finale."

"There will be two distinct periods. Everything before Avengers 4 and everything after. I know it will not be in ways people are expecting," he said, revealing that some of the MCU's original stars will not return for Phase Four, but that Marvel, which will have released 22 movies with Avengers 4, already has another 20 planned for the future.