Pop culture is dripping, dripping, with the occult.

The book and movie of “Twilight” have become instant megahits, HBO’s “True Blood” is one of the biggest shows on premium cable, and the novels of Charlaine Harris and Stephenie Meyer are haunting the bestseller lists.

Werewolves, then zombies, then vampires take turns as movie monster of the month. Left4Dead, a zombie-hunting video game, has sold more than 2.5 million units since it appeared last fall.

The supernatural is everywhere, and a wildly popular genre has been loosed from the vault: the supernatural or paranormal romance.

Why? Troubled times seem to raise the dead.

“The genre of fantasy is the ultimate escape,” says vampire-series author Richelle Mead. “Vampires play off that. I have heard people speculate that with the economic downturn … these books … serve a need for some larger escape.”

Or as Tony Allen-Mills put it in the Sunday Times of London: “The zombie has become the mascot of the global economic recession and a world shaken by terrorism.”

Some think the paranormal surge began shortly after Sept. 11, 2001. Danny Boyle’s zombie film “28 Days Later …” appeared in 2002. “Dawn of the Dead” arose in 2004, and George Romero’s epic “Land of the Dead” in 2005. “World War Z,” a zombie apocalypse novel by Max Brooks, has sold more than 200,000 copies since it appeared in 2006.

Zombies have been used to question, satirize or warn of the demise of contemporary culture. It’s hard to watch Romero’s classic “Night of the Living Dead” without seeing the angst of the Vietnam era. Vampire films often touch on divisive issues, such as AIDS in 1994’s “Interview With the Vampire” and racism in 1995’s “Vampire in Brooklyn.”

Since the earliest vampire films, such as the 1922 “Nosferatu” or 1931’s iconic “Dracula” with Bela Lugosi, they’ve been studies of those who are different, those on the outside with no way in. Vampires, says Alan Ball, producer of “True Blood,” can be “a metaphor for any kind of misunderstood and feared minority that is struggling for equal rights in a society, which of course makes it very easy to use metaphors for gays and lesbians, bisexual (and) transgender people.”

Or maybe the occult flowers as eras end. Katherine Ramsland, vampirologist and author of “The Science of Vampires” and “The Blood Hunters,” says, “I’ve been watching this trend for over 20 years, and I’ve seen that as a significant time period draws to a close — a decade, a century, a millennium — there is a surge of Gothic or supernatural focus. Vampire novels were also huge in the late 1980s and 1990s, and ‘Dracula’ was published in 1897.”

Forbidden love

It’s almost — eerie. In 1929 (oh, dark year!), William Seabrook’s “The Magic Island” spurred the pulpy fiction and films about zombies. In 1989, the splatter-punk anthology “Book of the Dead” began a decade of offshoots and imitators. To stretch the rule a bit, the mother of all zombie flicks, “Night of the Living Dead,” appeared in 1968. The TV series “Buffy the Vampire Slayer” aired from 1997 to 2003, nicely bracketing the turn of the millennium. And 2009 has seen the success of Seth Grahame-Smith’s novel “Pride and Prejudice and Zombies.”

“It may be partly due to a collective inarticulate sense of an era terminating,” Ramsland says, poetically. “We defy the feeling of closure and death by dancing dangerously with it.”

They don’t call it “supernatural romance” for nothing. At the core of many vampire and zombie tales, there’s a love story, either a human-human bond threatened by vamps, werefolk, demons, or zombies or a forbidden love across the line between living and dead. (Think of Buffy Summers’ bond with Spike.)

Mead, author of the young-adult “Vampire Academy” series (“Blood Promise” debuts this month), says, “The allure of the forbidden is what draws many people in, the romance between the immortal, sometimes dead, and always dangerous on one side, and the human on the other.”

Maybe, as paranormal-romance novelist Marjorie M. Liu says, “it’s the coming of age of people raised on ‘Buffy the Vampire Slayer,’ ‘Dark Shadows’ and ‘The X-Files.”‘ Or, as Mead says, “it’s the Harry Potter generation growing up and wanting a more sophisticated, edgier kind of world.”

Female empowerment root

Romance is the pulsating heart of the “Twilight” books by Stephenie Meyer, with the tortured love of Isabella Swan for the vampire Edward Cullen. Meyer patterns her books on classic romances: “Twilight” on “Pride and Prejudice,” “New Moon” on “Romeo and Juliet,” “Eclipse” on “Wuthering Heights” and 2008’s “Breaking Dawn” on “The Merchant of Venice” and “A Midsummer Night’s Dream.”

Last year was “Twilight’s” year. “Breaking Dawn,” the fourth novel in the quartet, sold 1.3 million copies its first day out. The 2005 book “Twilight” ended last year as the No. 1 bestseller, and the four books were 1 through 4 on USA Today’s year-end list. The film of “Twilight,” released last fall, grossed more than $382 million in worldwide box office and $157 million in DVD sales to date. Its sequel, “New Moon,” will be released in November.

“True Blood” is modeled on Harris’ “Southern Vampire Mysteries.” (The latest, “Dead and Gone,” debuted in May atop the New York Times hardcover list.) Season 1 followed the amour between telepathic waitress Sookie Stackhouse and vampire Bill Compton.

Liu, author of the Dirk & Steele and Hunter Kiss series, says supernatural romance “is about female empowerment. Shelters for abused women often distribute romance novels, and there’s a reason for it. Heroines who kill demons and hunt vampires — they’re tough chicks.”

Bob Wietrak, director of merchandising at Barnes & Noble, calls the paranormal romance craze “phenomenal.” Fully 16 percent of all romances Barnes & Noble sold last year were paranormal, and it’s “even more this year.”

Wietrak reports “an explosion of teen interest” as readers mature, stoked by TV and movie hits, which in turn are stoked by book sales. Fans read “fast, voraciously,” he says. “One of our challenges is to keep finding new books and new authors to satisfy the market.”

Bookstore, fan, author, and publisher Web sites link up in synergy, often producing explosive first-week sales: “There will be a huge surge when a title appears; we’ll sell 20 to 25 percent of our eight-week sales the first few days,” Wietrak says.

Zombie lands

At first bite, zombies seem less romantic than the undying passion of vampires. But some of the most popular zombie films, such as the hilarious shock-mocker “Shaun of the Dead” or the recent “Zombieland,” revolve around romance. And now we have the wacky success of “Pride and Prejudice and Zombies.”

The guy who had the idea is Jason Rekulak, editorial director of Quirk Books, in Philadelphia. Attracted to YouTube “mash-up” culture, he decided to combine two genres, one classic and the other pop-culture. On a sheet of paper he made a column of “public-domain titles we couldn’t get sued for mashing up, like ‘Moby-Dick,’ ‘Huckleberry Finn’ and ‘Pride and Prejudice.'” In another column, he listed zombies, monsters and figures from other horror genres. Then he drew lines between the columns.

“As soon as I drew the line between ‘Pride and Prejudice’ and zombies,” Rekulak says, “I knew we had a great title and a great idea.” Grahame-Smith signed on as writer, and the rest has been crazy.

Unbeknownst to Rekulak, they were about to surf the wave. “We were worried at first that the Jane Austen readers wouldn’t like the ultraviolent zombie mayhem, or that zombie readers wouldn’t like the Jane Austen passages. Turns out they go together!

“We started with a literary joke we thought might work, and we ended up taking advantage of a boom right now in supernatural romance. After ‘Twilight,’ we have the best-branded romance there is — everyone knows ‘Pride and Prejudice’!”