Jack Skellington is a character from all Kingdom Hearts games.
Known as the Pumpkin King sometimes, Jack is the biggest celebrity in Halloween Town. He is the star of The Nightmare Before Christmas.
The Movie
In The Nightmare Before Christmas Jack tired of the same routine every Halloween. While walking in the woods Jack finds a way into Christmas Town. Jack then decides to kidnap Santa Claus, and take his role in the celebrating. It ends in disaster and Santa is prisoned by Oogie Boogie. But in the end Jack defeats Oogie and saves Christmas.
In Kingdom Hearts, Jack tooks a liberal role of performing a scary Halloween, in this case, using the Heartless. Asking Dr. Flinkenstein to make a heart to the creatures so they can dance to the tones make the heartless go outlaw and break havok in Halloweentown. He request the help of Sora to find a solution. In Kingdom Hearts 2, he tooks his role of the movie.
In combat, Jack is prone to use his scary powers mixed with a good black magic, making him a splendid black mage. In the first game, he uses some black magic similar to Donald, yet in the second part he manipulate the magic with some goulish movements and fast touches of claws.