The Marvel Cinematic Universe has brought a number of superheroes to the big screen, which means that they've had to add a number of actors to the big screen as well.
Over all of the 20 movies to come out of the MCU, Marvel has made some truly fantastic casting decisions. Unfortunately, they have also made some rather poor casting decisions that might need to be rethought.
From Edward Norton to Terrence Howard, Marvel has already fixed a few of their casting issues. Additionally, they've even managed to replace actors for characters whose original actors did not want to return, like Hugo Weaving who played the villain Red Skull in Captain America: The First Avenger, but did not want to return to the role in Avengers: Infinity War.
Additionally, there are a number of actors whose contracts with Marvel Studios are just about up. While a number of these characters can just be written out, which we can expect to see in next year's Avengers 4, some of other characters are just too good to permanently kick out of the MCU.
Though some actors like Robert Downey Jr. and Chris Evans may be on their way out, it doesn't mean that Iron Man and Captain America have to leave too.
For every actor leaving and for every actor that needs to be kicked out of the Marvel Cinematic Universe, there is also a perfect actor who could fill the role.
With that in mind, here are the 13 Stars Who Should Leave The MCU (And 13 Actors Who Should Replace Them).
26 Should Leave: Robert Downey Jr.
Robert Downey Jr. may be the star of the MCU, but that isn't always necessarily a good thing.
Considering how well known Robert Downey Jr. is, he now charges Marvel loads of money for every single performance, with every appearance costing Marvel millions more than the last one.
Considering this factor and the fact that his contract is up after Avengers 4, there's no denying that Robert Downey Jr.'s time in the MCU is coming to an end, for better or for worse.
Hopefully, in the absence of Robert Downey Jr., Marvel can use the excessive money that they usually spend on his paycheck to improve the overall quality of their films in other departments.
25 Replacement: Jeffrey Dean Morgan
Jeffrey Dean Morgan has become an incredibly popular actor in recent years, mainly due to his role as Negan in The Walking Dead.
Because of this, not only would Morgan serve as an impressive replacement to Robert Downey Jr. in the mantle of Iron Man, but he would also be able to drive sales, which is arguably the most important factor on Marvel's mind.
The Walking Dead actor was previously reported to play a larger role in the DCEU, set to play the alternate universe version of Batman in Flashpoint following his appearance as Thomas Wayne in Batman v Superman: Dawn of Justice.
Unfortunately, it looks like the Flash movie will no longer follow the Flashpoint storyline, so this may be the perfect opportunity for Jeffery Dean Morgan to jump ship from the DCEU to the MCU.
24 Should Leave: Natalie Portman
Black Swan and Star Wars actress Natalie Portman appeared as the character Jane Foster in Thor and Thor: The Dark World. Unfortunately, Portman really didn't fit the role of Jane Foster well, becoming a bland love interest.
Whether this was at the fault of Natalie Portman herself or at the fault of the writers and directors remains to be seen, but regardless, a number of MCU fans were disappointed with her character.
If Marvel wants to continue developing Jane Foster in the movies like they did in the comics, perhaps a recasting is in order.
23 Replacement: Emma Watson
Harry Potter actress Emma Watson would be the perfect replacement for Jane Foster, especially if Marvel follows Jane's story line from the comics.
Recently in the comics, Jane Foster became the new Thor, wielding Mjolnir in the absence of Thor himself.
Emma Watson has proven herself time and time again to be a fantastic actress.
Additionally, she regularly takes stands against undeveloped female roles in movies as part of the feminist movement. Having Watson become the new Thor would work both for Emma Watson's ideals and as an entertaining and believable casting.
22 Should Leave: Ross Marquand
Earlier this year, Avengers: Infinity War brought the return of Red Skull, the HYDRA villain from Captain America: The First Avenger.
Unfortunately, rather than bringing back the original actor Hugo Weaving, Marvel replaced him with The Walking Dead actor Ross Marquand.
Rather than adding anything to the role of Red Skull, Marquand pretty much just did a Hugo Weaving impersonation.
While we didn't really get too much of a chance to see his performance, it still felt flat. If Red Skull were to return in the MCU down the road, it would probably be for the best if he was recast with a more viable actor.
21 Replacement: Liam Neeson
Taken actor Liam Neeson would be the perfect replacement for Red Skull in the MCU.
Not only does he have the right age range to look like an older, yet still physically able version of Red Skull, but his acting performances in the past would make him the perfect villain.
Neeson previously played a supervillain in Batman Begins, and he did a truly fantastic job.
If he were able to bring the same level of confidence in his evil actions that he had in Batman Begins to the character of Red Skull, the HYDRA villain could end up becoming a better antagonist than even Thanos.
20 Should Leave: Sebastian Stan
Bucky Barnes, the old war buddy of Steve Rogers / Captain America, has become an important part of the MCU since Captain America: The Winter Soldier in 2014.
In the near future of the MCU, Bucky has the potential to become an even more important character, as many fans predict that he will become the next Captain America.
Despite this, something just doesn't click with the current position that Bucky is in.
Despite being an incredibly vital character, Bucky's performances feel flat and unrelatable, which can be credited to both his writing and acting.
If Marvel hopes to have Bucky take up the mantle of Captain America, a new actor may be necessary for the role in order to keep audiences entertained and buying tickets.
19 Replacement: Kit Harrington
Game of Thrones actor Kit Harrington's schedule is set to open up a lot more in about a year after the final season of the HBO series.
Not only is Kit Harrington perfect for the part of Bucky, considering his impressive performance as Jon Snow, but he also has enough star power to carry on the Captain America franchise after the inevitable departure of Chris Evans.
Harrington's physical appearance and personality would make an incredibly entertaining interpretation of Bucky Barnes.
While it would be sad to see Sebastian Stan leave the role, it would hypothetically be worth it to see Kit Harrington become the next Captain America.
18 Should Leave: Marisa Tomei
Though Marisa Tomei may be a fantastic actress, a number of Marvel fans are still having difficulty seeing her in the role of Peter Parker's Aunt May.
While the reasoning for Marvel's decision to cast her makes perfect sense, as they are hoping to invest by casting an actress in her 50s rather than one in her 80s in order to keep her around long term, the casting comes at a cost.
Though Tomei gave a great performance in Spider-Man: Homecoming, it was still not believable enough for Spider-Man fans who adored the performance of Rosemary Harris in the original Spider-Man trilogy.
17 Replacement: Diane Keaton
Since it would be both unlikely and risky to bring the original Aunt May actress Rosemary Harris back to the role of Aunt May, there may be another option.
Academy Award winner Diane Keaton would be the perfect fit for the role of Aunt May in future Spider-Man movies.
Not only does Keaton have the perfect appearance and age for Aunt May, but she also has some incredibly impressive acting chops that would be just as good as, if not better than, Rosemary Harris's performance as May Parker from the early 2000s.
16 Should Leave: Paul Rudd
While Paul Rudd has done a phenomenal job as Scott Lang / Ant-Man in his three appearances over the years, there's no denying that he hasn't really done justice for Ant-Man from the comics.
While his performance as Scott Lang was great for his appearances so far, any further development of the character may require a different actor.
The best part of Rudd's performance as Ant-Man is his comedic style, which has made both of his movies entertaining.
However, later appearances may need an actor who can carry emotion just as well as comedy, which is something Paul Rudd may not be able to do.
15 Replacement: Simon Pegg
After the release of Ant-Man in 2015, many Marvel fans were curious to see what it would have been like had Edgar Wright stuck around to direct.
In a perfect world, Wright would return to direct a later Ant-Man movie, with Simon Pegg taking over as the new star.
Even if Pegg didn't replace Paul Rudd as Scott Lang specifically, it would still be great to see the British actor taking over the mantle of the size-altering superhero.
Whether he played an older Scott Lang, or even a younger Hank Pym, it would be truly entertaining to see Simon Pegg become the next Ant-Man actor, especially if Edgar Wright agreed to direct.
14 Should Leave: Ben Kingsley
Of all of the decisions made in the Marvel Cinematic Universe, the decision to make Ben Kingsley's portrayal of the Mandarin in Iron Man 3 a red herring is still not a decision that Marvel fans are ready to forgive.
The marketing for Iron Man 3 set up a huge fight with the Mandarin, who in the comics was a fantastic villain.
This left a number of Marvel fans disappointed when he ended up just being an actor.
Fortunately, the Marvel short All Hail The King teased that the real Mandarin from the comics may still exist in the MCU.
If this is true, then Marvel will need to find a new actor to replace Ben Kingsley in the role of the Mandarin.
13 Replacement: Ken Watanabe
Inception actor Ken Watanabe would be able to give a truly fantastic performance as the villain in a future Marvel movie.
He has played a number of phenomenal villain roles over the years, with a number of the villains being in positions of power.
With that in mind, Watanabe would surely be able to give an accurate portrayal of the Mandarin.
The biggest factor in Marvel casting the Mandarin was regulations from China, which would not let the movie release in their country if the main villain was Chinese. Hopefully, Ken Watanabe would be an exception to this rule, considering that Watanabe was born in Japan.
12 Should Leave: Glenn Close
In 2014, Guardians of the Galaxy introduced audiences to the Nova Corps, the "space cops" that have a number of similarities to DC's Green Lantern Corps in the comics.
Unfortunately, the version of the Nova Corps in the movies was incredibly under-powered and reserved, rather than being the super powered and incredible heroes that they were in the comics.
Part of the problem for the Nova Corps was their leader, who was played by Glenn Close.
While Close did a fantastic job performing as she always does, she didn't give the threatening or powerful vibe that is essential for the leader of the Nova Corps.
If Marvel were to give the Nova Corps their own movie, as many fans have been asking for, a recasting may be in order.
11 Replacement: Helena Bonham Carter
The best factors of Glenn Close's casting was her age and the fact that she was a confident female leader.
Actress Helena Bonham Carter would be able to bring these factors to the table as well, but would also be a believable active member of the Nova Corps considering her strong performances in the past.
All in all, it would be a lot more convincing to see Helena Bonham Carter kicking butt as the fearless leader of the super powered Nova Corps rather than Glenn Close, considering Carter's previous roles and her acting range.
10 Should Leave: Chris Evans
Like Robert Downey Jr., Captain America actor Chris Evans is on his way out. For years, Evans has discussed that he will be done as Steve Rogers after Avengers 4 with hopes to continue his career in other movies, or even as a director.
While it would be sad to see him go, it's practically inevitable. Even if Evans did want to stick around, it might end up being forced and unnecessary.
We've already seen Chris Evans a number of times as Captain America, so perhaps it is time to see someone else take up the mantle.
9 Replacement: Michael Jai White
Over the years, actor Michael Jai White has proven himself to be an incredible actor, having even played a couple roles in other superhero movies already.
Though his casting as Captain America would theoretically be incredibly controversial, it's almost guaranteed that he would be able to pull off an incredible performance.
White may be best known for his leading role in the 1997 Spawn, so he isn't a total stranger to starring in superhero movies.
It would be great to see Michael Jai White return to the spotlight yet again, but this time being dressed in red, white, and blue, and equipped with a shield.
8 Should Leave: Tim Blake Nelson
In 2008, The Incredible Hulk set up the Leader, one of the most dastardly Hulk villains from the comics with an over-sized brain.
In the movie, this character was played by Tim Blake Nelson. While we didn't truly see him as the Leader, we saw his origin with his mind expanding towards the end of the movie after being exposed to Bruce Banner's blood.
If this set-up for the Leader is paid off further down the road, it may be best if Tim Blake Nelson was replaced.
While Nelson gave a decent performance, it's not a performance that would necessarily fit for a threatening villain.
7 Replacement: Jim Parsons
The Big Bang Theory actor Jim Parsons would be a perfect fit for the Leader, should the villain make an appearance later in the MCU.
Parsons's performances over the years have been very intellectually-based, and it would be honestly great to see his smart and geeky acting style be taken up to a new level in a villain role.
Not only does his acting style fit perfectly for the Leader, but even his facial complexion seems to fit. For some actors, making their forehead over-sized just wouldn't work.
However, for whatever reason, it would be completely believable to see Parson with an over-sized brain and forehead.
6 Should Leave: Elizabeth Debicki
While Guardians of the Galaxy Vol. 2 was a truly fantastic sequel, a number of Marvel fans had issues with the villain Ayesha, played by Elizabeth Debicki.
Whereas the other villain Ego had an in-depth motivation and posed a legitimate threat, Ayesha's character felt flat and seemed more like a nuisance throughout the movie.
Based on the ending of Guardians of the Galaxy Vol. 2, it looks like Ayesha will make a return in Guardians of the Galaxy Vol. 3, possibly as the main villain.
Unfortunately, many fans may be disappointed with the antagonist plot of Vol. 3 unless some changes are made to Ayesha. One vital change may be recasting the actress entirely.
5 Replacement: Keira Knightley
Actress Keira Knightley has given a number of phenomenal performances over the years, both in dramatic movies like The Imitation Game and Pride & Prejudice, and fun fandom movies like the Pirates of the Caribbean franchise.
It would certainly be a lot of fun to see Keira Knightley bring both of these acting styles into the Marvel Cinematic Universe.
Not only is she an incredible actress, but Keira Knightley also has the perfect look to fit the "perfect" design of Ayesha's species introduced in Guardians of the Galaxy Vol. 2.
Even if they didn't have Knightley play Ayesha specifically, it would still be great to see her play one of the Sovereign in Vol. 3.
4 Should Leave: Sylvester Stallone
Guardians of the Galaxy Vol. 2 brought a fan favorite character to the big screen, but not in the way that fans wanted.
In the space opera sequel, Rocky star Sylvester Stallone played the former Guardian of the Galaxy from the comics Stakar Ogord / Starhawk. In the comics, Starhawk was like Star-Lord, but a bit more vintage.
When the Guardians of the Galaxy franchise started up, people wanted to see Starhawk join the super team, which is why many fans were disappointed that his appearance in the movies was as an older version of himself who had never even become a Guardian of the Galaxy.
3 Replacement: Skylar Astin
Skylar Astin would be the perfect replacement for Sylvester Stallone as Starhawk, especially if Marvel created a prequel movie to Guardians of the Galaxy showing the "original team" consisting of Starhawk, Yondu, and a number of the other characters who appeared in Guardians of the Galaxy Vol. 2.
Astin's charisma would make him the perfect leader for yet another space team.
While he is funny and snarky like Chris Pratt, he is still different enough to not make Starhawk feel like a cut-and-paste copy of Star-Lord, in order to make the movie feel more fun and original.
2 Should Leave: Tom Hiddleston
Based on the events of Avengers: Infinity War, it looks like Loki's return to the MCU would be unlikely.
However, Loki has come back from the grave so many times in the comics that it wouldn't be too much of a surprise to see him come back yet again in a future MCU movie.
In order to mix up his character and make his return feel more clever and original, it may be for the best that Loki does not come back in his Tom Hiddleston form.
In the comics, Loki has come back in numerous different ways, including as a woman and as a teenager. Perhaps one of those options would be better than seeing Tom Hiddleston in the role yet again.
1 Replacement: Finn Wolfhard
If Marvel chose to bring Loki back as a teenager like they did in the comics, Stranger Things and IT actor Finn Wolfhard would seemingly be the perfect actor for the role.
Wolfhard has given a number of great performances in the past and now has a decently sized fanbase, so casting him as Loki in a future movie would be an incredibly smart move for Marvel.
In the comics, Teen Loki joined the ranks of the Young Avengers and became one of their most prominent members.
Considering that Marvel Studios President Kevin Feige has expressed interest in a Young Avengers movie in Phase 4, seeing Finn Wolfhard play Teen Loki seems like a legitimate possibility.
What actors would you like to see depart the MCU? Who do you think would be a fitting replacement? Sound off in the comments!