As pretty much everyone is now aware, not all movies based on Marvel Comics characters take place in the same continuity. For example, Marvel Studios' Marvel Cinematic Universe is made up of eleven films that are mostly based around The Avengers and related characters, Fox's X-Men franchise is made up of seven movies based around the mutant heroes and, up until recently, Sony had the exclusive rights to Spider-Man's movies (which has, of course, recently changed, as the Webbed Wonder has joined the Marvel Cinematic Universe).
In the comic books, all of the characters within those different movie franchises regularly interact with each other (whether it be as allies or as enemies) and it is something of a shame that, at present, that can't happen on the big screen.
It might happen eventually (it's been rumoured to be on the cards a lot lately) but, for now, fans of the respective characters currently owned by Marvel Studios and Fox can only dream of seeing the live action Avengers crossing over with the live action X-Men and so forth.
With that in mind, let's take a look at the ten characters who are currently owned by Fox that would be the most awesome to see turning up in the Marvel Cinematic Universe.
Beast would be a great addition to the Marvel Cinematic Universe due to his links to a number of teams who either already appear in the franchise or who are likely to appear in the future. Classically an X-Men member, Beast AKA Hank McCoy - who has been portrayed by both Nicholas Hoult (young version) and Kelsey Grammer (older version) in Fox's X-Men franchise - has also been a key member of the Avengers, the Defenders and the Illuminati.
The Avengers are obviously the stars of the MCU, a version of the Defenders are due to appear in their own Netflix show soon and the Illuminati will surely arrive in the near future, given the number of the elite group's key members who have either already appeared in the MCU or are due to appear imminently (Iron Man, Captain America, Hank Pym, Black Panther, Doctor Strange, Black Bolt etc). Beast's mind and might would be of great help to the heroes of the MCU.
9 Ben Grimm
Ben Grimm AKA The Thing is, of course, famously a member of the Fantastic Four. Having been played by Michael Chiklis in the first Fantastic Four movies, the character is set to be portrayed by Jamie Bell in the upcoming reboot, but it's a real shame he can't appear in the Marvel Cinematic Universe at present.
In the comic books, Grimm has been a member of the Avengers and the Guardians of the Galaxy at different times (the latter was extremely recently) and he would be an awesome addition to either roster in the MCU. The main reason it would be great to see him in the franchise, however, is that seeing him having a live action fight with the Hulk - as he has done on a number of occasions in the comic books - would be absolutely superb.
8 Sue Storm
Classically another member of the Fantastic Four, Sue Storm AKA the Invisible Woman was portrayed by Jessica Alba in the first Fantastic Four movie franchise and she is due to be played by Kate Mara in the upcoming reboot. Like Ben Grimm, however, she has also been a member of the Avengers and it would be cool to have a female character as powerful as her in the Marvel Cinematic Universe version of the team (there's a lot more to her power-set than just being able to make herself invisible).
Moreover, she has also been a member of the all-female Lady Liberators - a team that has also included the likes of Black Widow, Scarlet Witch (both of whom are obviously existing characters in the MCU), She-Hulk, Spider-Woman, Medusa, Tigra, Valkyrie and Wasp - and it would be awesome to see an all-female team depicted in a live action movie.
7 Reed Richards
Like Ben Grimm and Sue Storm before him on this list, Reed Richards AKA Mister Fantastic is classically a member of - and the leader of - the Fantastic Four. However, he also has several key links to characters in the Marvel Cinematic Universe. Having been played by Ioan Gruffudd in the first Fantastic Four movies, he is due to be portrayed by Miles Teller in the upcoming reboot.
He has been an Avenger, a Defender and a member of the Illuminati in the comic books. His genius in science and technology is even greater than that of Tony Stark's and his knowledge (and even his elasticity power) would be a welcome addition to the MCU (God knows his genius would help against Thanos, but the likelihood of Richards arriving in time to face the Mad Titan is basically zero).
6 Johnny Storm
The final classic member of the Fantastic Four, Johnny Storm AKA the Human Torch would be a great addition to the Marvel Cinematic Universe. Having been played by Captain America actor Chris Evans previously, he is due to be played by Michael B. Jordan in the upcoming Fantastic Four reboot.
Although Johnny Storm hasn't been a member of any existing teams in the MCU, he's a frequent ally and friend of Spider-Man's and, with the Webbed Wonder heading to the franchise imminently, it would be really cool to see that relationship played out in live action. Moreover, his romantic relationships with the likes of the Inhuman Crystal and the Atlantean Namorita are some of the more interesting in comic books and those could potentially be explored in the MCU in future (plus, seeing Chris Evans interacting with a character he formerly played would be quite funny).
5 Professor X
Professor Xavier is, of course, the leader and mentor of the X-Men - but he's also much more than that. Famously played by both James McAvoy (younger version) and Patrick Stewart (older version) in the X-Men movie franchise, the powerful telepath plays a huge role in the Marvel universe.
A key member of the Illuminati (whose arrival in the Marvel Cinematic Universe is ultimately inevitable), Xavier also has links to the Defenders, the Shi'ar and a number of other teams and groups. His ability to control and read minds is something the heroes of the MCU lack (at least to his level and degree of intricacy) and he would represent a powerful ally - in more ways than one - to the likes of the Avengers in any future conflicts in the franchise, should he ever appear in it.
Where exactly can Marvel Studios go when it comes to topping an Infinity Gauntlet-wielding Thanos as the big-bad in the Marvel Cinematic Universe? Well, when it comes to power, they can't real go anywhere, as the already powerful Mad Titan wielding an item that essentially makes him God is hard to top, but if they want to simply come at the MCU's heroes with something bigger, they couldn't really do much better than Galactus.
Classically associated with the Fantastic Four, the planet-devouring force of nature has come into conflict with the Avengers on numerous occasions in the comic books and seeing a faithful adaptation presented in live action (i.e. NOT the horrible cloud version seen in Fantastic Four: Rise of the Silver Surfer) would be pretty awesome (and, given that the franchise is expanding into the cosmos, he would certainly fit right in).
3 The Silver Surfer
The foremost Herald of Galactus, the Silver Surfer pretty much appears wherever his master does. However, there is a lot more to the Silver Surfer than that and he could end up being a key ally to a number of the heroes in the Marvel Cinematic Universe, should he ever appear in the franchise.
After inevitably turning against his master (as he did in Fantastic Four: Rise of the Silver Surfer), the Surfer could go on to assist both the Avengers and the Guardians of the Galaxy - as he has done in the comic books so many times (though he has never actually been an official member of either team). He has, however, been a member of the Defenders (though not the version about to appear on Netflix) and, since the MCU cosmos is crying out for more heroes as more and more threats emerge, he could join the likes of Quasar, Beta Ray Bill and Gladiator in an MCU Annihilators team (which would be fantastic).
Aside from Spider-Man - who Marvel Studios have now secured, through an unusual agreement with Sony Pictures - the one hero that everyone would love to see fighting alongside the likes of Thor, Hulk, Captain America and Iron Man is Wolverine (it would also be cool to see Spider-Man and Wolverine in action together, as they have quite an interesting relationship in the comic books). Having been played so successfully by Hugh Jackman since the year 2000, it would be great to see him in the Marvel Cinematic Universe.
Wolverine is every bit as much an Avenger as he is an X-Men member and he would offer a level of ferocity that only the Hulk has offered to date. He'd be a great addition to the MCU's Avengers and his arrival would send box office numbers through the roof.
1 Doctor Doom
Doctor Doom is strongly associated with the Fantastic Four and was the ongoing villain in the first two Fantastic Four movies - played by Julian McMahon - and will appear again in the upcoming reboot - played by Toby Kebbell. However, he is also one of the most formidable and recurring Avengers villains and he's one of only a few non-cosmic characters who would be worthy of following Thanos as the big bad of the Marvel Cinematic Universe.
Doom is a threat on a number of levels - he's powerful politically, financially and physically and possesses a remarkable mind that makes him an expert in all things scientific and mystical. His schemes and power would be a legitimate threat to the entire heroic roster in the MCU and it would be absolutely fantastic to see him in the franchise.