6. Unaltered Beast
Ostensibly, the first appearance of Hank McCoy (Beast) in the film series was in X-Men: The Last Stand, where he appears as an advisor to the American president on mutant affairs and is played by Kelsey Grammar. Throughout the entire film, he appears as a blue-furred being, indicating that he has no ability to change his appearance at will. This is correlated by the events of X-Men: First Class, which is set around forty five years before The Last Stand. Showcasing Hank as a young adult with a human appearance, it depicts him as wishing to remove his mutation (superhuman speed, as well as prehensile feet), though the vaccine he creates to do so instead permanently transforms him into his beastlike state. He presumably stays in this form for the next four decades, though a blink-and-youll miss it scene from X2 throws a spanner into the works, as a very-much human Hank McCoy is seen on a television in a bar scene discussing mutant affairs. This minor discrepancy can probably be written off, given that it was a background event that a significant number of viewers wont even notice, but it does seem to indicate that the writers of the film series didnt initially do much in the way of forward planning.