One book I keep seeing come up as an essential October/Halloween read, is Roger Zelazny's A Night in the Lonesome October, often listed alongside Bradbury's Something Wicked This Way Comes. The book is broken into 31 chapters, one for each day of October, and I know some readers make a ritual of reading this book by reading a chapter per day as the month goes by. I started the book a little late in the month to do that, so I tore through it in only two days.
Zelazny is known for being quite imaginative and witty, and this, his final novel, serves as prime example. Many characters from film/literature are present in this Victorian era tale of magic and dark gods, and it's apparent that the author had quite a fun time paying homage to many of his favorites. The premise is simple: once every several years, the full moon falls on Halloween, which means a ritual can be performed to open the gates allowing the Elder Gods to inherit the Earth. Thus, The Game is born, and consists of occult figures who either act as openers, seeking to open the portal, or closers, seeking to thwart the openers and keep the status quo. The Game itself is a bit complex, with many bizarre rules and strange magic rituals. It is not clear who is on what side until later in The Game, and figuring out where one another stands is a big part of it.
Each player has a familiar: Jack the Ripper has a dog, Crazy Jill the Witch has a cat, the Count has a bat, etc. In perhaps the author's boldest move with the book, the narrator is Snuff, Jack's dog familiar, who was not always a dog. Most of the book consists of interactions between familiars, as they constantly trade information, sometimes sharing quite a bit, and sometimes holding back some important tidbits. It's interesting to see these creatures who may or not be rivals, working together throughout the book as the great ritual nears.
Although the book has undertones of horror: Elder Gods who want to inherit and remake the world in their image, vampires and werewolves, dark magic rituals and strange creatures from other dimensions, it's far from being a frightening book. It's a good, fun romp, and readers will enjoy the wit and the guessing of who is on which side right up until the night of the ritual itself. Half the fun is just seeing all the references in the book: Lovecraft's Elder Gods and Dreamlands, The Count (Dracula), The Good Doctor (Dr. Frankenstein), Larry Talbot (The Wolfman), Rostov (Rasputin), Morris and MacCab (Burke and Hare).
A Night In The Lonesome October is definitely a book that deserves to be dubbed "essential October reading". It has also inspired many tributes, most notably Neil Gaiman's Only The End of the World Again, which brings Larry Talbot to Innsmouth in an attempt to foil the Elder God's awakening again.
Being a big fan of the book, Lovecraft e-Zine editor Mike Davis started an annual tradition last year, with issue #18 being a tribute to Zelazny's novel. Zelazny's son Trent provides the introduction, and has given his blessing to make the issue an annual occurrence. The new issue should be available soon!