One summer, when I was nine or ten, I inherited a few thousand science-fiction and horror paperbacks from a friend of my mother’s. Over the next few months, in our damp and cobwebby basement, I raced through this library of slim, yellowing paperbacks from the fifties, sixties, and seventies, half of them with sexy space girls on their covers. There were mentalist sci-fi novels like “Dune” and “The Stars My Destination”; horror books with titles like “Night Thirst” and “The Howling”; genre-mixing novels about robot detectives, space cowboys, and galactic emperors. Some of these novels were bad, and others were great, but it didn’t matter—the main thing was that they were all defiantly and originally weird. It was the most mind-bending summer ever.

I thought of that experience last week while reading “Doctor Sleep,” Stephen King’s new sequel to “The Shining.” King’s new novel might have come straight out of that basement library. “The Shining” is introspective, austere, and unsettlingly plausible, which is why it comes to mind whenever you visit a creepy hotel, play croquet, or see an angry dad with his kid. But “Doctor Sleep,” which feels less like a sequel and more like a spinoff, is unapologetically fun, free-wheeling, and bizarre. It’s about a wandering band of psychic vampires who stalk clairvoyant children, kill them, and then inhale their “steam,” or psychic energy, for food. A grownup Dan Torrance—the little boy from “The Shining”—must help a young girl fight off these vampires, who have sensed her psychic abilities from afar and have chosen her as their meal of the week. In place of its predecessor’s unsettling familial violence, “Doctor Sleep” has thrilling gunfights, absurd satanic rituals, and wildly entertaining telepathic showdowns. In a chatty author’s note, King more or less admits that he didn’t try to make “Doctor Sleep” as terrifying as “The Shining”: “Nothing can live up to the memory of a good scare,” he writes, “especially if administered to one who is young and impressionable.” Instead, he says, he set out to tell “a kick-ass story.” He succeeded.

“Doctor Sleep” underscores an interesting fact about King: he’s not really, or not exclusively, a horror writer. If there were a Stephen King Plot Generator somewhere out there on the Web, it would work, most of the time, by mashing up ideas from all of what used to be called speculative fiction—including sci-fi, horror, fantasy, historical (and alternate-history) fiction, superhero comic books, post-apocalyptic tales, and so on—before dropping the results into small-town Maine. Often, too, some elements of the Western, or of Elmore Leonard-esque crime fiction, are mixed in. “Horror,” in short, is far too narrow a term for what King does. It might be more accurate to see him as the main channel through which the entire mid-century genre universe flows into the present.

Take “The Gunslinger,” from 1982, which is one of King’s best novels. It’s about a mysterious cowboy hero who pursues a “man in black” across a desert reminiscent of New Mexico or Utah. The novel weaves together knights, cowboys, demons, succubi, post-apocalyptic nuclear mutants, psychic tarot readers, and a Robert Browning poem; eventually, you realize that it’s all taking place in a sci-fi parallel universe. “The Langoliers,” from 1990, covers similar ground. It’s about a group of airline passengers who fly through a time rift, into the past. The twist is that the past isn’t the usual rewound version of the present; instead, it’s a dead, deserted world that exists for only a short while before it’s eaten up by terrifying monsters. The passengers—one of them is a girl with psychic powers; another has degenerated into a homicidal maniac—must find a way home before they are devoured. “The Langoliers” is classic King: a science-fiction premise (time travel) is complicated by horror-movie twists (monsters and a homicidal maniac) before some unrelated paranormal element (the girl with psychic powers) steps in to save the day. The novel is so engrossing that it never occurs to you that all of its elements are from disparate and perhaps incompatible genre traditions. King’s storytelling helps hide the joints. But a bigger factor is that King sees where different genre ideas have a common origin. Time travel, for example, has a natural relationship to psychic precognition: in the first case, you travel to the future, while, in the second, the future travels to you. Once King has pointed this out in a story like “The Langoliers,” you wonder why there aren’t more stories about time-travelling psychics.

King is still America’s dominant horror writer, but, for a while now, his wide-ranging, exploratory sensibility has felt at odds with the rest of the serious-horror landscape. Lately, our horror stories have tended, like our cable news shows, toward a despairing and nihilistic pseudo-realism. (Zombie movies, like “28 Weeks Later” and “World War Z,” have helped to set the tone.) King’s novels, meanwhile, have remained cheerfully preposterous. Perhaps for that reason, his ideas have found themselves at home on television, where serial storytelling gives their outlandishness room to breathe. “Under the Dome,” a new series on CBS, is based on King’s novel about—you guessed it—a small Maine town trapped beneath a giant dome. “Haven,” which is in its fourth season on SyFy, is based on “The Colorado Kid,” a King novella; the show is so steeped in King lore that its official Web site has a section devoted entirely to tracking its Stephen King references. “Lost” explored strikingly King-like territory, in a manner that will remind any King fan of “The Langoliers”; similarly, the criminally underappreciated “Fringe”—my pick for the best science-fiction show of the past decade—suggests what a King story might look like if it were untethered from some of his usual touchstones (addiction, mental illness, New England) and given a mad-science spin. J. J. Abrams, who helped create both “Lost” and “Fringe,” has turned out to be an influential fan. He’s optioned “The Gunslinger,” and his production company, Bad Robot, is reportedly in talks to develop “11/22/63,” King’s strangely moving novel about a man who travels back in time to kill Lee Harvey Oswald. These shows are finding new ways to express one of the central ideas in King’s fiction: that the universe is more mysterious, freaky, and bad-ass than we know.

King’s success as a genre fantasist is obvious and undeniable—it’s absolutely central to who he is as a writer. And yet critics and writers, in embracing King, have often done so by ignoring his otherworldliness and lauding his realism. Margaret Atwood, for example, writing about “Doctor Sleep” in the Times Book Review, argued that, “down below the horror trappings,” the book was “about families,” and especially about the family as a place where two kinds of anger, “righteous” and “destructive,” express themselves. In 2003, when the National Book Foundation awarded King a Medal for Distinguished Contribution to American Letters—the year before, the winner had been Philip Roth —the writer Walter Mosley, in introducing King, praised “his almost instinctual understanding of the fears that form the psyche of Americag’s working class. He knows fear,” Mosley said, “and not the fear of demonic forces alone but also of loneliness and poverty, of hunger and the unknown.”