For the first time all of Marvel's characters are appearing in one massive comic.
It's to celebrate the superhero creators' 80th anniversary.
Captain America, Iron Man and The Hulk all feature in the 89-page epic.
But it's the appearance of what looks like DC Comics' Batman that has really got people talking.
In one picture fans think they can see his famous black hood from behind.
Batman had his 80th anniversary earlier this year so this might explain the crossover!
The comic is called issue #1000 and has been created by 80 creative teams from the company's history.
Each page of the issue tells a story of an important event in Marvel's past.
The first story in the comic is about the creation of the Human Torch in 1939 - who appeared in the very first Marvel comic.
The Human Torch shone a light on the future of superheroes! 1939 was also the year that Marvel was created.
Other tales, include a page set in 1944 where Captain America explains why he fights and there's even a story dedicated to Iron Man's suit in 2008.
2008 was also the year the latest Marvel film franchise was launched. The final film in the series Avengers: Endgame came out earlier this year.