The big Marvel Cinematic Universe crossovers generate a lot of excitement prior to their release. The internet is suddenly flooded with multiple rumors, fans create crazy theories that might just wind up being true, and everybody wonders if their favorite hero might perish in an epic yet heartbreaking battle. However, one of the most exciting parts is trying to guess what characters will make it onto the big screen, especially in a time when the multiverse is at the center of the stage.

Remember how excited we were all at the prospect of watching the return of Andrew Garfield and Tobey Maguire's Peter Parkers in Spider-Man: No Way Home? Slowly but steadily, fans are starting to get the same feeling in anticipation of Avengers: Doomsday. While the movie's official cast announcement already gave us a glimpse of what to expect from Earth's Mightiest Heroes' upcoming adventure, Kevin Feige has revealed that there's room for more characters to make an appearance.

To take things a step further, we have the release of Avengers: Secret Wars further down the line, which will undoubtedly feature no shortage of multiversal cameos. Anyone can make an unexpected comeback, and it seems that will be exactly the case as revealed by a new report.

According to industry scooper Alex Perez (via The Cosmic Circus), the upcoming Avengers movies will bring back old Marvel heroes that weren't initially a part of the MCU. When asked if there's a chance audiences will see the "old Fantastic 4, old Spider-Man (before Tobey Maguire), or characters from non-MCU that had shows or small projects?" Perez answered with a definite "yes". Now, it's a matter of discovering just who might make it into the final cut.

There's been a lot of discussion surrounding the idea of watching the Council of Reeds in the MCU now that The Fantastic Four: First Steps is upon us and the multiverse will certainly play a part in its story. If that were to be the case, then it would be the perfect opportunity for Ioan Gruffudd to portray the role of Mr. Fantastic after an almost 20-year hiatus. Granted, it's worth noting that the beloved actor has stated that he "hasn't been invited" to Avengers: Doomsday yet. However, there's always Secret Wars to look forward to... or he could be simply trying to pull off an "Andrew Garfield" and deceive us all to make us feel genuinely surprised once he returns.

An interesting idea mentioned in the Alex Perez question is whether we'll get to see any Spider-Men that predate the Sam Raimi adaptation. When it comes to actors who portrayed a live-action version of wall-crawler before Tobey Maguire, there are only two candidates: Nicholas Hammond (who played Peter Parker in The Amazing Spider-Man 1970 series) and Shinji Tōdō (who brought Spidey to life in the Japanese Spider-Man TV show). While any of them could very well join Earth's Mightiest Heroes, we should also take into consideration another seemingly unlikely option.

There were reports that animated Marvel characters could show up in the battle against Doctor Doom in a Space Jam-esque crossover. If that were to be the case, then it would open the door for many versions of the web-slinger to appear in the movies as well. Much to fans' surprise, Peter Parker from Spider-Man: The Animated Series made a comeback during the events of X-Men '97. Now, maybe there's a chance that his particular story will be followed up on in the biggest superhero crossover to date.

Deadpool & Wolverine already reintroduced non-MCU heroes to the big screen after many years. Aside from the X-Men, fans welcomed Blade and Elektra with such open arms that you'd imagine Marvel would want to try to replicate some of that magic yet again. As simple as that, Nicolas Cage's Ghost Rider or even Ben Affleck's Daredevil might team up with the Fantastic Four and New Avengers to prevent the collapse of the multiverse.

Avengers: Secret Wars could be not only a culmination of the MCU's Multiverse Saga, but also of the story of many iconic heroes we've watched through the years. Hopefully, Disney will do them all justice, and they will each go out with a bang.

Avengers: Doomsday will be released on December 18, 2026.