Casting can make or break any movie, but the stakes are even higher when it comes to the superhero genre. Could you imagine, for example, if Christopher Nolan's The Dark Knight had starred Jared Leto in place of Heath Ledger?
Now try to picture the X-Men movies with anyone other than Hugh Jackman in the role of Wolverine. It might be difficult to imagine but it very nearly happened. And on more than one occasion too.
Back in 1990, when Stan Lee was in discussions an X-Men movie that would have been directed by Kathryn Bigelow with Carolco Pictures, Bob Hoskins was the frontrunner to land the part of Logan.
Fast-forward a few years to Bryan Singer's X-Men movie, and Russell Crowe was in the frame for the part. He would ultimately turn it down, citing an eagerness to do something less action-orientated after Gladiator but recommended his friend, Jackman, for the role.
However, despite delivering an impressing audition, the studio opted for Dougray Scott over the little-known Australian. What they never accounted for was the fact that Scott was already in production on Mission: Impossible 2.
Handpicked by Tom Cruise to play the movie's villain, mounting delays on the John Woo-directed sequel ultimately forced Fox and Singer to ditch Scott at the last minute and hire Jackman in his place.
It proved to be a masterstroke and an example of perfect, if somewhat fortuitous, casting. There are other examples of this throughout the X-Men movie universe.
It's not always worked out quite so well, however, with plenty of talented and not-so-talented stars appearing out-of-sorts and out-of-place throughout the franchise.
With that said, here are the 18 Casting Decisions That Hurt The X-Men Movies (And 17 That Saved Them).
Hurt: Vinnie Jones as the Juggernaut
As far as movie tough guys go, Vinnie Jones certainly looks the part. This isn't by accident, either. Jones had a formidable reputation as a soccer star from his days in the Premier League and was able to parlay some of that same fearsome charm into a movie career.
Starting with Lock, Stock and Two Smoking Barrels, and continuing with films like Swordfish, Jones established a reputation for playing characters whose actions spoke louder than words.
However, casting Jones as Juggernaut and giving him a bunch of lines, including one referencing an internet meme, just didn't look as good on screen.
Hearing the painfully wooden Jones say the words "I'm the juggernaut, b***h" still sends a shudder down the spine of any self-respecting fan.
Saved: Ian McKellan as Magneto
Though the likes of Christopher Lee and Terence Stamp were linked with the role during pre-production on 2000's X-Men, Ian McKellen ended up bagging the part having worked with director Bryan Singer on his previous effort, Apt Pupil.
He played a war criminal hiding out in American suburbia in that movie in a role that was good practice for the duality of iconic Marvel villain - charming and courteous one minute, unpleasant and aggressive the next.
Having a Shakespearean actor also gave this Magneto a suitably theatrical feel, while McKellen's on-screen chemistry with Patrick Stewart has been fundamental to the success of the franchise.
Hurt: Rebecca Romijn as Mystique
Rebecca Romijn was already well established as a model and celebrity in her own right prior to her casting in Bryan Singer's first X-Men movie.
It represented her first major movie role, though it was one that proved an unwelcome distraction.
Wearing a "costume" that consisted of little more than some blue makeup and some strategically placed prosthetics, this Mystique may have been an effective silent assassin, but her lack of lines or anything in the way of character development left Romijn serving as little more than eye candy.
This is a shame, as Romijn would later prove herself a capable actress with roles on shows like Ugly Betty.
Saved: Patrick Stewart as Professor X
As the yin to Ian McKellen's yang in X-Men, Patrick Stewart's suitability for the role of Professor Xavier wasn't just down to his chemistry with the Magneto actor. It felt like he was born to play the part.
Not only does he bear a striking resemblance to the Professor Xavier of the Marvel comics, but he also conveys the same kind of academic gravitas as the character.
This is something that was no doubt helped by his classical training as an actor.
The fact that he'd already served with distinction as Captain Jean-Luc Picard on Star Trek: The Next Generation also showed his versatility and range with the kind of "imaginative" material that some actors would avoid.
Hurt: Shawn Ashmore as Iceman
The depiction of Iceman in the original trilogy of X-Men movies must surely rank among the most disappointing of the entire franchise, largely because he isn't given a whole lot to do.
Injecting the character with a little attitude or some sense of fun might have helped remedy this, but actor Shawn Ashmore largely played it safe.
Deployed in a secondary role, Ashmore's Iceman is painfully vanilla, with the actor struggling to assert himself on the screen as little more than an occasional love interest.
Ashmore has spoken of a willingness to return to the role following the intriguing comic book storyline that saw Iceman come out as gay. Unfortunately, this looks likely to happen.
Saved: Hugh Jackman as Wolverine
It's difficult to imagine anyone other than Hugh Jackman as Wolverine. This is how good he's been in the role across a 17-year spell playing the Marvel icon.
As arguably one of the most popular and therefore pressurized comic book roles, Jackman has shone during the good, bad, and ugly parts of the X-Men movie franchise.
Looking and sounding the part is no fluke, either. Jackman's diet and fitness regimen for the role is the stuff of legend and imbues his performance with a physicality befitting of a trained, military "weapon" of a man, equipped with adamantium claws et al.
Jackman's theatrical background also ensures that he nails the emotional intensity of Logan time and time again.
Hurt: Oscar Isaac as Apocalypse
When the first images of Oscar Isaac as Apocalypse surfaced online, fans were far from happy.
After years waiting for one of the X-Men universe's most feared villains to arrive on the big screen, it looked like they were getting something more commonly found in your standard episode of Mighty Morphin' Power Rangers.
Some nifty post-production work might have improved his appearance, but it did little to enhance Isaac's surprisingly stilted performance.
Apocalypse was supposed to be the most feared of all the X-Men villains but, physically speaking, Isaac is simply too small.
Saved: Ryan Reynolds as Deadpool
X-Men Origins: Wolverine is one unholy mess of a movie. Not even the presence of Hugh Jackman opposite the equally excellent Liev Schreiber can salvage proceedings.
This is a shame, because there are moments where the movie is genuinely enjoyable. Some of them involve Ryan Reynolds' Wade Wilson, who packs enough action and wisecracks into one short scene early in the movie to highlight why a Deadpool movie could work.
It may have taken a few more years of negotiations, some stellar scripts, and a leaked screen test, but the reality is there would be no Deadpool movies without this guy and the decision to cast Reynolds in the first place.
Hurt: Nicholas Hoult as Beast
Nicholas Hoult is a more than capable actor and someone who can turn his hand to a variety of genres with aplomb. He's just not Hank McCoy.
Sure, he's got the geeky, scientist aspects of the character down, but McCoy always had a little more clout to him than the English actor brings, both physically and in terms of on-screen personality.
This is why someone like Kelsey Grammer was arguably better suited to the part.
Finding a young actor that might have fit that criteria might have been a challenge, but Hoult just doesn't have the necessary star quality for what is an important role.
Saved: Halle Berry as Storm
Angela Bassett may have been the first choice for the role of Storm, but Halle Berry proved to be an inspired choice as the X-Men heroine.
Despite a string of critically-acclaimed performances in lesser productions, major mainstream success had eluded Berry until then.
This changed with X-Men, where Berry pulled off the role of Storm to perfection despite being criminally underused.
With a magnetic onscreen presence and similar looks to Storm, her deliberately subdued delivery and general air of maturity and gravitas added something a little different to the X-Men mix.
Should she have got more screen time and her own plot? Definitely, but she was still effective.
Hurt: Jennifer Lawrence as Mystique
Jennifer Lawrence may be one of the standout actresses in Hollywood right now and a worthy Oscar-winner to boot, but her casting as Mystique in X-Men: First Class is problematic.
Mystique, for one thing, was always a supervillain in the comics rather than the conflicted anti-hero she is portrayed as in the prequel movies.
All too often Lawrence falls into old habits too, with her version of Mystique coming off as little more than a shape-shifting rejig of The Hunger Games' Katniss.
Also, for all the positivity of positioning a female actress at the fore of proceedings, does it really have to be the revealing Mystique again? Are there no other suitable female mutants?
Saved: Michael Fassbender as Magneto
Capable of conveying the same mix of charm and snarling ferocity as his elder counterpart Ian McKellen, Michael Fassbender also imbues his Magneto with the raw menace you might expect from a younger version of the X-Men supervillain.
His relationship with on-screen friend-turned-adversary James McAvoy's Charles Xavier is crucial to the success of X-Men: First Class.
While McKellen succeeds in presenting the world-weary finished article that is Magneto, Fassbender's is a Magneto-in-the-making – raw, angry, and more humane but altogether more unpredictable than his older self.
In a somewhat ironic assessment, Fassbender is also a suitably magnetic onscreen presence.
Hurt: Tye Sheridan as Cyclops
Having made his name as a teen star in dramas like The Tree Of Life, Mud, and Joe, the casting of Tye Sheridan as Cyclops in X-Men: Apocalypse feels like a bridge too far.
One of the main problems with Bryan Singer's movie is the sheer number of superhero characters crammed into proceedings.
This means that Sheridan has limited time to shine as the young Scott Summers, and he's no James Marsden.
It's by-the-numbers stuff, but Sheridan doesn't feel like a natural fit for the goody-two-shoes Cyclops - he'd have been better off as Spider-Man - and lacks any real chemistry with Sophie Turner's more effective Jean Grey.
Saved: Anna Paquin as Rogue
Having won an Oscar at the tender age of 11 for her standout performance in The Piano, Anna Paquin was in danger of becoming just a footnote in Academy Awards history until she landed the role of Rogue in Bryan Singer's X-Men.
She went on to deliver a multi-layered performance that's crucial to the success of the first movie as the film's central female protagonist and the character who viewers root for unreservedly.
Paquin plays it to perfection, coming off as naïve and likeable, while grappling with her dangerous new powers in a script that incorporates themes around puberty and adolescence.
Hurt: Olivia Munn as Psylocke
Olivia Munn is many things. Having started out as a television presenter and occasional correspondent, she's been able to build on a whole host of hilarious small screen appearances with a string of sizeable roles in comedy movies.
Movies like Ride Along 2 and Office Christmas Party capture her at her comedic best. None of that comes to the fore in X-Men: Apocalypse, though, with Munn playing it straight and struggling to emote.
As a villain, she's not particularly fearsome, either.
That said, Munn handles the physicality of the Psylocke okay. It's just that she seems to sleepwalk her way through her limited dialogue.
Saved: Kelsey Grammer as Beast
When plans of Bryan Singer's first X-Men movie were first rumored in the late '90s, Kelsey Grammer was undoubtedly the standout pick to play the Beast, aka Hank McCoy.
Grammer was at the peak of his powers on Frasier at the time.
He brought box office clout to proceedings, as well as the necessary mix of physicality and charisma needed for the role.
Though he did eventually get the part, it was a touch too late, coming in arguably the weakest X-Men-centric movie released to date, X-Men: The Last Stand.
Hurt: Tyler Mane as Sabretooth
The decision to cast Tyler Mane as Sabretooth in the first X-Men movie may have been born out of necessity rather than anything else.
With budgets proving limited on what was the first major movie outing for the Marvel superhero troupe, the former wrestler turned actor was apparently the best option available.
Mane floats through the movie as a doe-eyed simpleton of a mutant.
As far as wrestlers-turned-actors go, he's solid enough. As far as straight up actors go, he's got room for improvement.
Sabretooth deserved better and would eventually get better, thanks to Liev Schreiber.
Saved: Alan Cumming as Nightcrawler
As one of the standout performers in the brilliant X2, Alan Cumming came close to missing out on the part of Nightcrawler due to scheduling conflicts.
At one point, Ethan Embry was close to landing the part before a delay in production paved the way for Cumming to return.
The Scottish-American actor proved a revelation. Already capable of speaking German fluently, Cumming did his research, revisiting previous comic books and illustrations of the character and patiently sitting through nine hours of makeup.
It was all worth it, with Cumming delivering an authentic and engaging portrait of one of the most unique characters in the X-Men universe.
The only shame is that we didn't see more of him.
Hurt: Taylor Kitsch as Gambit
Someone somewhere in Hollywood really wanted Taylor Kitsch to be a star. What other reason is there for the string of dud movies featuring Kitsch in a lead role?
Sure, he'd shown himself to be capable of playing a high school football star on the excellent Friday Night Lights, but there was always a suspicion that role wasn't a massive stretch.
Though the Canadian Kitsch played ice hockey in his formative years, he was far from slick as the Cajun card-throwing mutant Gambit.
Having waited patiently for the character to be brought to the big screen, this felt like a disappointment and another nail in the Wolverine: X-Men Origins coffin.
Saved: James McAvoy as Professor Xavier
James McAvoy must rank among the most versatile leading men in Hollywood, so it's hardly a surprise to see him excel as the younger incarnation of Professor Charles Xavier.
He came off as a younger, more idealistic version of the character previously portrayed by Patrick Stewart.
The pair have plenty in common. Both are British, and both are classically trained, giving Professor Xavier the necessary academic smarts and sharpness required for the role.
McAvoy instils his Xavier with a little more edge too - the kind of edge that begins to be worn away over the course of McAvoy's three outings as the character to date.
His on-screen chemistry with Michael Fassbender is predictably impressive too.