Let's face it- the X-Men franchise isn't exactly known for it's continuity. Don't get me wrong- I hold the series in very high regards, only coming in second on my superhero favorites list to the Marvel Cinematic Universe, and I understand that changes must be made. But several of the changes are simply mind boggling. For instance, we've seen Professor Xavier walking as an older man TWICE, the first time being in the beginning of X-Men 3 and the second time being at the end of X-Men Origins: Wolverine. This is really bizzare, because Professor X was paralyzed as a young man, as we saw in First Class. Out of all of these continuity flaws and changes, the ones that catch my eye most often are the drastic changes made to the characters, so in light of the upcoming Days of Future Past, We'll be taking a look at the most drastic character changes in the series.
In X3, Beast is portrayed as pretty much a hairy blue man, As apposed to the comics ape or feline type forms. This however is changed for First Class, Giving the character a more animalistic, cat like appearance ( this ones my personal favorite). In Days of Future Past, Beast is seen more ape like, closer to his appearance in X3. This however, may be do to a serum Beast will use in DoFP that allows him to temporarily take on his human appearance.
The changes made to Sabretooth are definitely drastic. In the original X-Men, Sabretooth is very animalistic. He has long hair, black eyes, and uses grunts and growls more frequently than words. In Origins:Wolverine, He is given more of a clean shaven look. He looks and acts more human, and even his powers are different; He is seen running on all fours, retracting his claws sort of like wolverine, and even has a mild healing ability ( he was able to survive a firing squad, yet was told later he could not survive having adamantium bonded to his skeleton like Wolverine).
3. Bolivar Trask
Finally on our list, we have Bolivar Trask. First before I get started, nothing I say here is meant to be offensive. In X3, Bolivar Trask is played by Bill duke, who is 6'4 and African American. In Days of Future Past, Trask will be portrayed by Peter Dinklage of Game of Thrones fame, who is 4'5 and caucasian. The character's physical appearance between the films could not be more different. The Bill Dukes portrayal has now been retconned in favor of Dinklage's. Who will make the better Trask? We'll find out when Days of Future Past is released on May 22nd!