Warning: This article contains spoilers for Doctor Strange in the Multiverse of Madness.
Marvel Studio's latest cinematic event is Doctor Strange in the Multiverse of Madness and it comes with its fair share of exciting cameos and fan service that's bound to get MCU audiences talking. But not only does it bring back old characters from forgotten stories, but it also features one of Marvel's most bold and daring storylines to date.
Benedict Cumberbatch reprises the titular role of Doctor Strange, as he travels through the multiverse in an attempt to stop Elizabeth Olsen's Wanda Maximoff from tearing reality apart in search of her lost children. It's an extremely intense story, and the shocking cameos throughout the film make it all the more thrilling.
Pizza Poppa
Although some of the cameos in Multiverse of Madness seem to be setting up for future events, it appears that Bruce Campbell's appearance was little more than a fun recognition of the actor's long-standing friendship with director Sam Raimi. Campbell has been a part of many of Raimi's films since playing the protagonist of his horror classic The Evil Dead.
In this film, Campbell appears briefly as Pizza Poppa, a New York street vendor who bumps into Strange and Chavez during their journey through Earth-838. Seeing as Strange has no reason to return to this universe, it seems unlikely that Campbell will return (unless Raimi gets ahold of another Doctor Strange sequel).
Maria Rambeau's Captain Marvel
After being captured by Earth-838's version of Baron Mordo, Doctor Strange is introduced to a secret band of heroes known as the Illuminati. One of these heroes is Captain Marvel, but not the one that fans know from Earth-616. This iteration sees Maria Rambeau instilled with the powers that Carol Danvers has in Earth-616.
Back in the main universe, Maria Rambeau died of cancer shortly after setting up S.W.O.R.D. and losing her daughter to the snap. It seems unlikely that version of Rambeau will return, so there's no real reason to see her again in the future.
Ultron
It's not totally clear whether or not the Ultron Bots from Multiverse of Madness actually hold Ultron's consciousness or whether they're just built in his image - but either way, they were a welcome inclusion to the Illuminati's headquarters. Ultron was one of the best villains in the MCU, so it's not a huge surprise that he returned in some form.
That being said, it seems very unlikely that Marvel will use Ultron again any time soon. Not only did the Ultron Bots appear in Multiverse of Madness, but a variant of Ultron was also revealed to be the main villain in Disney+'s What If...? - so maybe that's enough Ultron for now.
Captain Carter
Captain Carter was first introduced in animated form during Marvel's What If...? show, but Multiverse of Madness saw her make the transition to live-action as a member of the Illuminati. However, she doesn't last very long as she's quickly sliced in half by her own shield at the hands of a dreamwalking Scarlet Witch.
Although Peggy Carter is dead in the main timeline of Earth-616, there are plenty of other places where Captain Carter could appear in the MCU. With a second season of What If...? currently in development, this seems like the most likely option for Carter's return.
Charles Xavier
Multiverse of Madness's marketing did a poor job of keeping Patrick Stewart's return as Charles Xavier a secret, but it was still entertaining to see. However, he appears neither as an Earth-616 version nor the version from the X-Men films - but rather as the leader of the Illuminati on Earth-838.
This means that there's likely still a version of Charles Xavier in the main MCU timeline, even though audiences haven't seen him yet. Fans know that the X-Men are planned to join the Marvel Universe at some point, so Charles Xavier would be a great way to lead into this (even if it's not Patrick Stewart in front of the camera).
Rintrah
Although Rintrah might not have been the most exciting cameo for casual MCU audiences, more astute Marvel fans will recognize the character from Doctor Strange's adventures in the comics. Despite not even being named in the film, his presence represented a clear move towards a more comic-accurate story for Strange.
In Multiverse of Madness, Rintrah is a Master of the Mystic Arts and an apprentice at Kamar-Taj, so it seems likely that he'll still be there next time fans see Strange and Wong at work. Even if he only ever appears as a side character, his existence is proof that the MCU is incorporating more and more details from the comics.
Black Bolt
Although the Inhumans TV show was received pretty poorly, Anson Mount's performance as Black Bolt was undeniably one of its strongest and most memorable assets. And although it seems that Inhumans does not take place within the MCU, the law of the multiverse suggests that Earth-616 could still have some variation of the character.
The fans' reaction to Mount returning as Black Bolt has been positive so far, so it makes sense that Kevin Feige and the Marvel team would want him to return in the future. There are plenty of opportunities to bring him back, in spite of the fact that his Earth-838 counterpart is dead.
Reed Richards
Many agree that John Krasinski's Reed Richards will almost definitely show up again in the MCU, although it's not totally clear when or how. The character is one of the most popular superheroes in all of Marvel Comics, most famous as the patriarch of the Fantastic Four and one of the founding members of the Illuminati.
A Fantastic Four project is currently in the works at Marvel, but it hasn't been announced whether or not Krasinski will be reprising his role from Multiverse of Madness. A recast is definitely possible due to the infinite possibilities of the multiverse, but the fact that Krasinski was such a popular fancast makes it likely that he'll stick around.
Clea
If there's one character that Multiverse of Madness makes clear will be returning, it's Charlize Theron's Clea. She appears during the film's mid-credits scene, in which she takes Doctor Strange through a portal into the Dark Dimension and makes note of the third eye that he's gained after using the Darkhold.
In the comics, Clea is a huge part of Doctor Strange's story. She's the Sorcerer Supreme of the Dark Dimension, the niece of Dormammu, and eventually a love interest to Strange himself. It's unclear what her role in the MCU is going to be, but it's sure to be fresh and exciting.