However the currently untitled upcoming fourth Avengers movie plays out in 2019, it seems safe to presume that Marvel's Phase 4 is going to have some significant changes from the previous phases. At least some old favorite characters (or at least their current actors) will be gone for good, while others will definitely continue. We know there's one more Guardians of the Galaxy movie, another Black Panther and multiple Spider-Man movies in the works. Presumably we'll be seeing more of Captain Marvel beyond her debut movie, and possibly more Doctor Strange as well. Beyond just old favorites returning, however, Phase 4 is certain to introduce new characters to the big screen.

At this point, though, casting news for such new characters is sparse, with only vague rumors abounding. Many of the biggest new characters for Phase 4 have barely started casting. Eternals, supposedly the big new cosmic centerpiece of Phase 4, is still in early development, and it's unclear if the discussed Ms. Marvel movie is even that far along. The 14 casting rumors on this list, however, might give you an idea of what we can expect for new stars in the MCU, as well as one star you can be certain we won't be seeing.

15 THE X-MEN CAST JOINS THE MCU

This rumor has been going strong ever since Disney entered talks to purchase 20th Century FOX. Official plans to merge FOX's X-Men films with the Marvel Cinematic Universe can't begin until the end of antitrust investigations, a process which will take until the end of 2018 at the earliest and could potentially destroy or alter the proposed deal. That said, surely Kevin Feige has been thinking long and hard about the possibilities of introducing mutants to the MCU.

One theory even proposes Eternals is a placeholder for an X-Men movie Marvel can't officially announce yet.

Adding the X-Men to the MCU would introduce tons of new characters. Would Marvel recast all these parts, or would producers, as rumored, simply import the current movie ensemble into the MCU? The latter would actually make a lot of sense with how FOX is handling the franchise. The impending Disney deal doesn't seem to be doing anything to slow down FOX's production of X-movies. Eight more are already scheduled for release between 2019 and 2021. If we're guaranteed so many more FOX X-Men movies, the easiest way to to handle the characters' introduction to the MCU would be to somehow merge the MCU with the movies that FOX is already making.

14 TOM HARDY AS WOLVERINE

Tom Hardy and Wolverine

Of course, there is one mutant Marvel is going to have to recast. Hugh Jackman is done with playing Wolverine, and honestly, bringing him back after the near-perfect swan song of Logan would just be insulting. Theoretically, you could follow Logan by passing the torch to Dafne Keen's X-23 as the new Wolverine. That would certainly make for a great movie, but does Disney and its generally family-friendly MCU (Netflix shows aside) want to connect so directly to the darkest and most mature of the prior X-Men movies? Maybe the X-23 movie could be a great last hurrah for the purely FOX-controlled franchise, but once Disney and Marvel start exercising control over the mutants, they're going to want a new Wolverine.

So who should be cast for the new Wolverine? Many people have ideas. Scott Eastwood wants to take on the role, while Travis Fimmel finds his way onto most fan-casting lists. The best choice, however, would be the one Hugh Jackman himself wants to take over the role: Tom Hardy. He's an ideal fit, a talented actor and rising star with experience in the action and superhero genres. He's also maybe the best in the world at acting under masks, a skill which would come in handy if Marvel goes with a more comics-accurate costume. Really the only question is if he can fit the commitment into his schedule, especially if, as rumored, he's also in consideration to be the next James Bond.

13 WILSON BETHEL AS BULLSEYE

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Unlike other more speculative entries, this rumor is 90% confirmed at this point. It's also for a TV show rather than a movie, so you can argue whether it technically belongs on a Phase 4 list, but with solid rumors so scarse, this feels like it's worth discussing on this list. It was confirmed in November 2017 that Wilson Bethel, known for his roles in Generation Kill and The Young and Restless, is playing "Steve," an FBI agent in the third season of the Netflix Daredevil series.

The casting call for "Steve" emphasized "the darkness inside himself," implying his character would be a villain.

Early speculation implied Steve might be the character of Sin-Eater, but on May 16, the website That Hashtag Show reported that the character Bethel's playing is in fact Bullseye. This report has yet to be confirmed by Marvel, so it's still in the "rumor" bin, but other news sites are reporting this as well, making this rumor appear to be an extremely believable one. Supposedly this interpretation of Bullseye is based on the reimagining of the character as an ex-military marksman in Jason Aaron's Punisher MAX series rather than the traditional Earth-616 version of the character.

12 NATALIE PORTMAN AS THOR

natalie-portman

Natalie Portman's Jane Foster has been notably absent in recent MCU movies. She was only mentioned in passing in Age of Ultron when Thor and Tony Stark were comparing their girlfriends, and she was completely absent from Thor: Ragnarok. The explanation for this is that Natalie Portman doesn't want to be in the Marvel movies anymore, being burned by the experience of Thor: The Dark World and in particular how the studio fired original director (and eventual Wonder Woman helmer) Patty Jenkins. Yet when asked by Huffington Post about Jane Foster's fate at the end of Infinity War, Anthony and Joe Russo refused to answer the question claiming it was a "potential spoiler."

The implication there is that Jane (and Portman) might be back, either in Avengers 4 or later in Phase 4. Perhaps Portman's merely had a change of heart inspired by the studio's efforts to increase behind-the-scenes diversity. But just returning for a cameo or a normal "girlfriend" role seems too small to be a dramatic "spoiler," so looking to the comics, many are predicting that there's something huge in store for Jane. For a while in the comics, Jane Foster wielded Mjolnir as her own Thor, and Jane in the movies coming back as a new Thor would be a return worth getting hyped for.

11 WILLIAM HURT AS RED HULK

William Hurt as General Thunderbolt Ross in a dark gray room in Captain America: Civil War.

Of all the films in the MCU, the one least essential to following all the other movies is easily The Incredible Hulk. The second film in the grand shared universe experiment, it's the one the least people have seen if box office results are anything to judge by. The Hulk character got softly rebooted when the studio replaced Edward Norton with Mark Ruffalo for The Avengers, and little in The Incredible Hulk has paid off in other films. Other than Hulk and Iron Man, the only character from that movie to return in future movies was Thaddeus "Thunderbolt" Ross, played by William Hurt. Ross pushed the Sokovia Accords in Civil War, arresting Captain America's group of defectors, and continued to pressure Rhodey to arrest Cap's team in Infinity War.

For all the times we've seen Ross, however, the movies have yet to introduce his most dramatic manifestation from the comics.

After dedicating his life to hunting the Hulk, Ross became the type of creature he most hated himself. The Red Hulk was first introduced around the time of the Incredible Hulk movie's release, and Marvel has talked about doing a Red Hulk movie in the past; James Gunn was in talks to direct one before he took on Guardians of the Galaxy. With Ross returning as a significant presence in Phase 3, many speculate Marvel's building up to some serious Hulking out in Phase 4.

10 MARK HAMILL IN GUARDIANS OF THE GALAXY VOL. 3

Mark Hamill in The Last Jedi

Sometimes, Twitter is good for the world. Not often. Usually it's an unusable hellsite filled with spam, trolls and obnoxious discourse, but sometimes it's actually useful. Sometimes, rather than sending threats to celebrities, people actually send them nice ideas! Such was the case when on February 25, a fan by the name of Ian Fee tweeted to James Gunn suggesting he find a role for Mark Hamill in Guardians of the Galaxy Vol. 3.

Gunn responded to idea tweeting, "I think @HamillHimself lives around the corner from me in Malibu so he can just come over and we can talk about it over a cup of coffee." Hamill in turn responded enthusiastic about the possible casting, writing, "I would be happy to do so, both as a good neighbor & an unemployed actor." So there you have it, both creatives want to collaborate, and it seems very likely they will. Hamill's role in GotG Vol. 3 could be a cameo or there could be a major character Gunn has in mind for the actor. It's also possible these early talks could ultimately lead to nothing, but wouldn't it be cool to see the man who played Luke Skywalker show up in Marvel's big Star Wars-influenced space opera series?

9 JOHN BOYEGA AS... SOMEONE

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Mark Hamill isn't the only Star Wars star who might show up in the MCU's Phase 4. Finn might be joining Luke Skywalker. While Hamill's talks with James Gunn as of this writing might not have progressed beyond Twitter conversations, John Boyega has officially met with Marvel in talks about playing... someone. Who he'd play, we don't know. The only fact that's certain is that, despite early speculation, he's definitely not going to be playing Blade (or, if he does end up doing so, he certainly doesn't want to now).

As for who Boyega might end up playing, fans continue to speculate about various characters he might be a good fit for. Eli Bradley and Miles Morales have been thrown about as possibilities, but Boyega's a bit too old to play comics-accurate versions of those heroes. He could be The Blue Marvel, if Marvel wants to build up to an Ultimates movie, or Captain Britain, if Marvel's OK with racebending that role and wants to give Boyega a chance to use his authentic accent. And of course, there's the huge roster of obscure characters available for use in Eternals, which Marvel would be wise to fill up with talented recognizable actors like Boyega.

8 WESLEY SNIPES BACK AS BLADE

Wesley Snipes posing with his sword for Blade II

Why doesn't John Boyega want to play Blade? Easy answer: he wants Wesley Snipes to! At AwesomeCon 2018, in fact, Boyega went so far as to say that, "it would be a spit in the face of Wesley if I took Blade." Clearly, this man wants his Wesley Snipes Blade movies! So, too, has Snipes himself spoken out about wanting to do a fourth Blade movie. He told The Hollywood Reporter that, while he would if asked, he's unlikely to take on a different role in the MCU because he says that the fans want him to return to the role.

Perhaps Blade's return would make most sense as a Netflix series.

The old Blade movies would actually be quite easy to retcon into the MCU in comparison to the X-Men movies, which would likely require some sort of big "universes collide" event movie to work. It's been a long enough time that the bad aftertaste of Blade: Trinity has been mostly forgotten and people are becoming nostalgic for the first two movies. The one real obstacle is that the MCU films have all been generally family-friendly PG-13 affairs, while the Blade series is distinguished by its R-rated ultraviolence. Perhaps Blade's return would make most sense as a Netflix series, where the MCU's darkier and edgier characters tend to end up.

7 ZAC EFRON AS ADAM WARLOCK

Perhaps the most significant of the mid-credits scenes in Guardians of the Galaxy Vol. 2 was the one revealing the ultimate being, Adam Warlock, in hibernation. Adam's role in the MCU is going to be very different from the comics, in which he wielded the Soul Gem and played a big role in the Infinity Gauntlet storyline, but nevertheless this character is a big deal. Fans keep speculating about different actors playing Adam. James Gunn has been quick to shoot down rumors about the likes of Tom Cruise and Matthew McConaughey playing the character, saying he needs to cast younger to portray this "perfect man."

Marvel entered talks with Zac Efron back in 2014. Given Efron hasn't been announced for any of the many films released since then, it's possible the talks went nowhere. It's also possible that they did go somewhere, but his role got pushed back. Such has been the case with Adam Warlock's role; he was originally set to be a character in GotG Vol. 2, but Gunn cut him down to just that credits Easter Egg when the script became too complicated. Adam could be in hibernation for a while, and there will be new stars who could play him when the time comes for him to enter the MCU. Efron, however, is still in the excellent physical condition needed to play the role, and he has the skills as a comedic actor needed to work amongst the Guardians cast.

6 ANT-MAN'S DAUGHTER RECAST

Emma Fuhrmann Cassie Lang

IMDb updates aren't always trustworthy, and on their own wouldn't typically be worth taking seriously. However, That Hashtag Show investigated a recent update to Avengers 4's IMDb page and claims sources back up the rumor that Emma Fuhrmann will be playing Cassie Lang, Scott Lang's daughter. In the Ant-Man movies, Abby Ryder Fortson played Cassie. Fuhrmann is six years older than Fortson. This would seem to back up the theory, inspired by set photos and the powers of the Infinity Stones, that Avengers 4 is going to be a time travel story.

Introducing an older Cassie Lang also might imply the direction Marvel wants to go for its major Phase 4 team-up.

In the comics, Cassie Lang joins the Young Avengers following her father's death. Utilizing Pym Particles for powers akin to her father's, she took on the superhero moniker of Stature (she'd later go by Stinger). Presumably most of the older Avengers are going to end up either dead or retired by the end of Avengers 4. In light of that, a Young Avengers movie would be an easily marketable way to carry on the classic characters' legacies while also introducing fresh faces and more diversity among the characters.

5 MATTHEW MCCONAUGHEY AS NORMAN OSBORN

Norman Osborn Matthew McConaughey

Matthew McConaughey has been circling roles in the MCU for a while. He was an early choice to play Ego in Guardians of the Galaxy Vol. 2, with the art department even drawing him into early concept art. Kurt Russell ended up taking that role, and speculation he could play Adam Warlock was quickly shot down. Still, there's another role McConaughey has been rumored for which he could still end up playing: Norman Osborn, the original Green Goblin.

If this rumor turns out true, it seems unlikely that McConaughey will be in the Spider-Man: Homecoming sequel coming summer 2019. It's confirmed Jake Gyllenhaal is officially in talks to play Mysterio, Michael Keaton's Vulture is expected to return and there's at least one other villain Sony has tried to cast for Homecoming 2. Overloading a sequel with too many villains already killed two separate Spidey movie series. Adding Green Goblin, a villain we've already seen on-screen twice courtesy of Willem Dafoe in Spider-Man and Chris Cooper in The Amazing Spider-Man 2, seems like overload. However, Tom Holland's confirmed that he's going to be doing a third Spider-Man film, and a McConaughey Goblin could work as a great final enemy for this trilogy.

4 BRYAN CRANSTON AS AN ORIGINAL VILLAIN

Whenever an actor is reported to be talking with Marvel, fans immediately start discussing which comic book character fits that actor best. However, not every MCU scene-stealer comes from the comics. Phil Coulson was an original creation, as was Luis in Ant-Man, and while he eventually evolved into Vision, J.A.R.V.I.S. was never part of comic book lore either, at least not as A.I. Bryan Cranston has long been a favorite pick for the role of Norman Osborn among fan-casters.

However, if he ends up in a Marvel movie, don't expect him to be playing Osborn... or anyone recognizable from the comics!

At the premiere of his 2015 Oscar nominee Trumbo, Bryan Cranston told reporters for the U.K. paper Metro that he wants to play "some big superhero villain in some Marvel classic." As for which villain he'd play, he had an interesting request for the story team at Marvel: "Create one from scratch… I don’t know what I would do but it would be nasty." It's not out of the realm of possibility that he could be pulled in to play some preexisting Marvel villain. A lot of more obscure comics characters end up being so radically reenvisioned in the MCU that they could essentially be deemed "new" characters in all but technicality. However, if Marvel's planning on making any truly "nasty" original villains for Phase 4 or beyond, the studio knows who it needs to call.

3 KENDRICK LAMAR AS THE NEXT BLACK PANTHER VILLAIN

Kendrick Lamar's soundtrack for Black Panther stands both as one of the best and most financially successful movie soundtrack albums in many years. It would not be a shock if "All the Stars" or "Pray for Me" ends up taking the Best Original Song Oscar in 2019. Naturally, the Pultizer Prize-winning rapper is going to stay involved for the sequel. If he has his way, his involvement might go beyond the music into starring in the movie! In a BBC Radio interview shortly after the first film's release, he volunteered to play a villain in the next one, saying, "If I could, I'd play a Killmonger for sure."

Which of King T'Challa's enemies would Lamar be best suited for playing? Fans have thrown around several names. Achebe, a deranged revolutionary whom creator Christopher Priest described as "the Joker to Panther's Batman," is the most common guess. Other theories about who it could be include the hitman Killjoy, the demon Mephisto and the clairvoyant King Cadaver. Even Namor the Sub-Mariner, not a traditional villain but someone who did launch a massive attack on Wakanda at one point, has been mentioned. Namor, however, seems less likely than the other options given certain complications...

2 DWAYNE JOHNSON AS NAMOR

dwayne johnson fast and furious featured

This is the least likely rumor that still hasn't been officially ruled out. Namor the Sub-Mariner is in a weird place rights-wise where Universal technically owns the movie rights despite not doing anything with them. In 2016, Joe Quesada told Kevin Smith on the Fat Man on Batman podcast that Marvel did have the movie rights to Namor sorted out. Two years later, however, Kevin Feige told IGN the legal situation with Namor was still "complicated."

It's a match which has stuck in fans' imagination for a reason.

The Dwayne Johnson rumors also date back to when Universal was believed to be developing a Namor movie, so if Marvel makes a Namor movie, the casting plans could easily be going in a completely different direction. The very idea of Marvel pursuing a Namor movie seems, if not unlikely, a lower priority compared to all the better-known heroes they do own or are on the verge of acquiring from FOX. Still, if Aquaman is a huge hit, one could easily imagine Marvel being determined to compete with Namor, and if they want instant attention from a public unfamiliar with the Golden Age anti-hero, Dwayne Johnson is one of the most universally beloved movie stars working today. It's a match which has stuck in fans' imagination for a reason.

1 NOT HAPPENING: MATT DAMON AS KRAVEN THE HUNTER

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In addition to Mysterio and the Vulture, Kraven the Hunter is the third villain who's officially been talked about to star in the Spider-Man: Homecoming sequel. We don't know who's playing Kraven yet, or even if Kraven is still included in the final draft of the screenplay. What we do know is that at one point Kraven was in fact going to be a major player in the movie, and that Sony wanted a major star to take on the classic villain role. One star who officially turned down the offer to play Kraven? None other than Matt Damon.

It seems Sony is very concerned about getting A-list stars to play the villains in their Spider-Man films, beyond Marvel Studios' usual level of concern. At this point in movie history, star power isn't as reliable a box office indicator as brand power, and few brands are as powerful these days as Marvel Studios. For Sony, however, Spider-Man is one of their only truly reliable brands amidst a string of box office disappointments. The thinking is that A-listers can still give guaranteed blockbusters an extra boost into becoming even bigger phenomenons. However, according to The Tracking Board's Jeff Sneider, Damon officially passed on the role.