Though this short post-Hallow's End holiday is often forgotten, you should be sure to check out Day of the Dead (which lasts from November 1-3rd) in order to pick up the Macabre Marionette. Previously the Marionette could only be used during the holiday, but this year it's a full-fledged battle pet to add to your collection.
To get started, go to your race's home city -- or try neutral cities Shattrath or Dalaran -- and head for the graveyard. There you'll find Catrina offering the quest The Grateful Dead. Follow a short quest chain and you'll wind up with your very own Macabre Marionette for the keeping. For a longer quest walkthrough, check out the Macabre Marionette writeup on WarcraftPets. And good luck -- though for a quest chain this simple, you probably won't need it.