The Mayor is the two-faced "leader" of Halloween Town. He has two faces which show his emotions. They switch often between sad and happy. Although he is the mayor, he says he cannot do anything without Jack Skellington's help. The Mayor's exact words are that he is only an "elected official", implying that, even though he is the mayor, he has very little authority.
The Mayor has two split personalities, happy and sad/worried. He looks up to Jack as the town's hero. Nothing much else is known about his personality, except that he is happy when his face is on the skin-colored side and he has a smile on his face. But when his skin is grey and his smile turns to a frown, it means he will be worried or sad.
The Mayor is rather short, especially when compared to Jack. His head is cone-shaped and displays the two faces he is most notable for. One face (as well as his hands) is peach-colored, with rosy cheeks and a face set in a permanent smile. The other face is bone-white and has a mouth set in a permanent frown (the teeth of which are pointed) with green lips and yellow eyes. There is an seam of some sort around the mouths of both faces because in the claymation for the movie, the mouths were replaceable to make the mayor talk.
His top hat is gigantic, being the same height as the himself, but very thin. The Mayor's body is also cone-shaped, with his body ballooning outward before ending on short, stubby legs with very tiny feet. He dresses in a black suit with a white undershirt and black-and-white pinstriped pants. He wears a pendant or bow-tie shaped like a black widow spider, though it only has six legs and the notorious red hourglass marking is on the spider's back and is much more detailed than in real life.
There is a red ribbon with the word "MAYOR" printed on a white center pinned to the left breast of his blazer. He is never seen without his short, metal megaphone that he uses to issue orders, announcements, and, more often, call for help from Jack.
During Jack's rehearsal in the town square, the Mayor introduces Jack while the Search Ghosts perform. After Dr. Finkelstein's first attempt at creating a heart, the Mayor comes into the entryway to the lab in distress and tells everyone that the Heartless have started rampaging. He later appears in the graveyard and tells Sora and company how to obtain the "surprise" ingredient, the Jack-in-the-Box.
When Halloween Town is overrun by Heartless, the Mayor tries yelling at the Heartless to leave the town square. This proved to be ineffective, so he calls for Jack stating that "I'm only an elected official!".
After Oogie Boogie is defeated by Sora, the Mayor arrives in Christmas Town searching for Jack. He says that he had been looking everywhere for Jack. Just as he and Jack begin planning for the next Halloween, the Gate appears before Sora.
In the movie, The Nightmare Before Christmas, he gets the people of Halloween Town and himself ready for Halloween by asking Jack Skellington for help. He has two faces. One of his faces is happy while the other may be either sad or angry. His split personality type situation was possibly inspired by The Strange Case of Dr. Jekyll and Mr. Hyde, and he is a literal description of the phrase "two-faced politicians".