Any good comic book fan should know at this point that a movie version of their favorite story is going to take some liberties. By now, it's disappointment that simply comes with the territory. (Looking at you, 'Watchmen.') Along these lines, purists are raging about 'X-Men: First Class' before it even hits theaters.

And they're not all wrong. The film, a prequel about the young mutants' beginnings in the 1960s, is wildly different from the storylines in the comics. Though it alludes to the earlier films ('X-Men: The Last Stand' and 'X-Men Origins: Wolverine'), it doesn't abide by them. The story is altered enough to make any 'X-Men' fan gasp out loud in the theater. (As this one did!)

Here are five HUGE differences between the comic books and 'X-Men: First Class.'

(SPOILERS AHEAD!)

5. Havok's Backstory and Family History

In the comics: Havok is Cyclops' younger brother. He is able to generate powerful plasma blasts, an ability he has had difficulty controlling. He was raised in an orphanage and met the other X-Men in college while studying geophysics.

In 'X-Men: First Class': Havok (Lucas Till) is a young prisoner sprung by the X-Men as an ally after being found using Xavier's Cerebro (though in the film, Cerebro was created by Hank McCoy). It's hinted that he is Cyclops' father.

4. Banshee's Age and Relationship With Moira

In the comics: Banshee is an Irish ex-Interpol agent who is significantly older than the other X-Men. His power is the ability to scream supersonically, allowing him to fly and break things. He meets X-Men ally Dr. Moira McTaggert and falls in love with her.

In 'X-Men: First Class': Banshee is a redhead, but he's American-made. He's also a teenager, making any sort of romance with grown-woman Moira pretty grody. He's portrayed as the youngest of the baby X-Men. At least the actor playing him, Caleb Jones, tried to incorporate some of his comics knowledge into the role.

As Jones told IGN in May: "I know there's a love connection in the comics with Moira, so I try to look at her just a little bit differently, you know, when I can. I know Mystique cuts my vocal chords later on. I don't know if they're going to do that in the movies, but therefore I make it a little bit so that if that does happen later on, for any of the fans watching, they can notice that."

3. A Teased Romance Between Beast and Mystique

In the comics: It never happens. Mystique, first of all, is way older than she's portrayed in the movies. In the comics, she's around and having relationships (with ladies, no less!) at the end of the 19th century. Beast, meanwhile, was not born blue like Mystique was, but uses his scientific experiments to make himself more, well, beast-like. He sprouts blue fur, and his already large hands and feet grow and his senses get stronger.

In 'X-Men: First Class': Beast and Mystique are both blue, both teenagers and both feeling like outcasts. Naturally, they're poised to get down. But somehow, Mystique becomes the catalyst for Beast's experiment. He wants to make them both normal, and in his attempt he turns himself even more beastly. The things you do for love (that you never did in the comics)!

2. Xavier Becoming Paralyzed

In the comics: An alien named Lucifer, disguised as the devil, was acting as the advance scout for an invasion by his race, and Charles Xavier foiled his plans. In retaliation, Lucifer dropped a huge stone block on Xavier, crippling his legs.

In 'X-Men: First Class': Uh, we don't blame them for taking a different route here. Moira aims to shoot Magneto, who deflects her bullet in Xavier's spine. He is accidentally paralyzed.

1. Xavier's and Mystique's Childhood Friendship

In the comics: They didn't know each other prior to becoming enemies. Mystique would hardly have been a teenager when Xavier was in his late 20s.

In 'X-Men: First Class': Xavier meets Mystique when they're both children and they grow up together as pseudo-siblings. He's a big-brother figure to her in the films and is one of the first people to extend kindness to her in her natural blue form. It's a total re-imagining of their backstory and the biggest change from the comics to the film.

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