Adaptational Jerkass

Film

 * Death Note: While Light has always been a murderous Villain Protagonist, the live action film series makes him even worse. He becomes more evil more quickly than either the anime or manga, to the extent he's perfectly willing to personally kill his own father to prevent the Death Note from being organized.

Web Original

 * Stupid Mario Brothers has several examples, all Played for Laughs:
 * Far from the happy-go-lucky hero of the games, Mario here is a selfish Lazy Bum who does such things as refuse to cut his vacation short to rescue Peach from Bowser again, on top of.
 * Princess Peach of the game series is a Nice Girl through and through. This Peach is a whiny, nagging Spoiled Brat.