The Nightmare Before Christmas

Halloween Town is a fantasy world filled with citizens such as deformed monsters, ghosts, ghouls, goblins, zombies, mummies, vampires, werewolves and witches. Jack Skellington, a skeleton with the title of "Pumpkin King", leads them in organizing the annual Halloween holiday. However, Jack reveals he has grown weary of the same routine year after year, and wants something new. Wandering dejectedly in the woods, he stumbles across seven trees containing doors leading to towns representing various holidays, and accidentally opens a portal to Christmas Town. Impressed by the bright and cheery feeling and style of Christmas, Jack presents his findings and his understanding of Christmas, to the Halloween Town residents. However, they fail to grasp his meaning and compare everything to their ideas of Halloween. Jack is dismayed that no one understands the feeling of Christmas, and obsessively studies the holiday but fails to find any further explanation of it. He ultimately decides that it's unfair for Christmas Town alone to enjoy the feeling and announces that he and the citizens of Halloween Town will take over Christmas this year. Read more on Wikipedia.