Geek Love by Katherine Dunn
Opening line: "'When your mama was the geek, my dreamlets,' Papa would say, 'she made the nipping off of noggins such a crystal mystery that the hens themselves yearned toward her, waltzing around her, hypnotized with longing."
Brief synopsis: The Binewski family run a traveling carnival populated by their children, who have all been genetically modified to have birth defects so they can freak show acts. Narrated by the youngest Binewski daughter, Oly -- an albino humpback dwarf -- the novel recounts the rise and fall of the family business, and their bizarre and morally deprived daily life.
What makes it scary: Geek Love isn't technically a horror novel. There are no paranormal elements, no manufactured scares. But it's a gruesome, sick book, more depraved than you can even imagine, and all the more delightful because of it. Dunn -- who recently passed away -- achieved cult status after the release of the book, which was notably beloved by Kurt Cobain, and prompted director Terry Gilliam to declare, after reading it, "It made me ashamed to be so utterly normal."
Geek Love is a sprawling story about the grimy underbelly of Americana, where the horror elements are so normalized that they don't always register. A cult springs up around one of the Binewski siblings, Arty, who convinces his followers to amputate their limbs to achieve "purity." There are deprave sex acts, moments of incest, and murders. The scariest imagery comes from a man with a mutilated face who joins the carnival after an act of violence. But Geek Love is also surprisingly tender at times; you hate the deranged Binewskis, but admire their solidarity, and their utter rejection of normalcy. It's horrific for how it conditions the reader against that normalcy. It's hard to look at the world the same way after reading this book.