Jack Skellington is the Pumpkin King of Halloween Town

Jack Skellington is the Pumpkin King of Halloween Town, and it's his ideas that make Halloween different and more exciting every year... But inside he felt empty, unsatisfied and tired of people screaming. One day he came into Christmas Town by chance.

There, he saw all the exciting things and brought a lot of things back to study. Finally, he decides to use his creativity to bring a new Christmas to everyone. He lets Lock, Shock and Barrel kidnap Santa Claus, and he never thinks that his efforts will not bring joy to The hot Christmas.
Instead, he frightens humanity. Finally he realizes that Sally, the girl who makes his Christmas costumes, is the one who cares about him the most...