LOS ANGELES—Headstrong Bella is in love with a vampire. Zoey has a crescent moon seared onto her forehead, the mark of a fledgling bloodsucker. Sixteen-year-old Ever can hear people's thoughts. Calliope is, reluctantly, Death's daughter.

All are modern female heroes written by women, read by women and not only obsessed over by teenagers but also their older sisters and mothers. The economy may be deeply troubled, but urban fantasy novels about vampires, werewolves, zombies, supernatural creatures, blood and romance are booming, and women are sinking their teeth into them in ravenous numbers.

"We're living in a frightening time. I don't know if it's an escapism as in there's scary stuff out there so let me control it through the medium of reading," says Amy Clarke, a lecturer at the University of California, Davis who teaches science fiction literature.

"There's dreaming of being with a vampire or werewolf, but there's always the danger of crossing over. I think it's a post-feminist way of taking on power."

The trend gathered steam with Bella Swan and her conflicted romance with gorgeous vampire Edward in Stephenie Meyer's four-book "Twilight" series, which has sold more than 53 million copies worldwide since the first book's release in 2005, according to publisher Little, Brown and Company. Meyer's newest, the more adult-themed "The Host," has 2 million copies in print domestically.

Call it dark escapism with a racy flair. The "Twilight" explosion, including its hit movie version, has deepened the needs of women urban fantasy novel readers.

Other authors are jumping in: P.C. Cast and her daughter Kristin's popular "House of Night" vampire series; Alyson Noel's "Immortals" books: the "Sookie Stackhouse Southern Vampire Mysteries" novels by Charlaine Harris, which inspired the TV series "True Blood" on HBO; Richelle Mead's "Vampire Academy" trilogy; and books by more than half a dozen other female writers.

The genre's popularity is bigger than just books, says P.C. Cast.

"With women, this is reflecting a shift in our society," Cast said in an interview from her home in Tulsa, Okla. "I've seen a big shift, especially in my classroom, with women standing up and demanding respect. That's in every woman, whether 16, 26, 56."

"Our fiction is also reflecting that because we're writing the fiction. We've given ourselves permission to be successful. We're also giving ourselves permission to have fun," said Cast, a single mother who taught high school English for 15 years before focusing only on writing.

Her five "House of Night" books, starting in 2007 with "Marked," follow the adventures of Zoey Redbird, a high school student marked to be a vamp, who must enter the House of Night. Described as a "vampyre finishing school," it's filled with bratty girls, cute guys and no end of drama.

Cast enlisted the help of daughter Kristin, 22, to ensure that the teen-speak in her stories reflected current vernacular as opposed to the author's "inner '70s teenager saying things that were so not cool."

It paid off.

There are 5.5 million copies of the five "House of Night" books in print in the United States and the series has been on The New York Times list of best sellers for 63 weeks, according to publisher St. Martin's Press. "Tempted," the sixth book, is due out in October. The series has been optioned by Empire Pictures, with a film script in the works.

"Vampires are super sexy. Vampires and teens have a lot in common. Teens have surging hormones, vampires have surging blood lust. Teenagers think they're immortal," Cast said.

And for older women, says UC Davis' Clarke, "hot blooded" has taken on new meaning.

"All of the stuff I've read have some pretty heated sex scenes in them, and that brings people into the world of it," Clarke said. "The teens haven't had sex yet and the mothers have, and it's maybe not as good as it was."

Noel's "Immortals" series focuses on the telepathic teen Ever, who gains her abilities after surviving a car accident that kills her family. Brooding and lonely at a new school in sunny California, she meets handsome immortal Damen. They're drawn to each other like magnets.

"All of us older people reading these books magically survived high school even though we thought we wouldn't," Noel said in an interview from her home in Laguna Beach, Calif. "To be young and beautiful and have power forever is pretty alluring in this society."

More than 700,000 copies of the two "Immortals" books are in print, according to St. Martin's Press. The first book, "Evermore," has been on the Times list for 23 weeks since its release in February. The second book, "Blue Moon," was released this month, with book three scheduled for January 2010.

Mead's "Vampire Academy" series has 1.5 million books in print, according to publisher Penguin Razorbill Books. The fourth book in the series comes out in August.

Amber Benson, who earned a huge fan base as witch Tara on the cult-hit TV show "Buffy the Vampire Slayer," which ended in 2003, channeled her love of urban fantasy into a trilogy, with the first book released this year by venerable science fiction and fantasy publisher Ace Books, an imprint of Penguin.

In "Death's Daughter," Calliope Reaper-Jones is a 25-year-old immortal who works in New York City. After her father, the CEO of Death, Inc., is kidnapped, she must run the family business.

"That was the beauty of Buffy, this female protagonist who looked totally harmless but could do all these amazing things and was trying to be a real person at the same time. She definitely influenced Calliope and her journey," says Benson, as she sits in her Los Angeles home beneath a sign reading "Old Friends to Read, Old Friends to Trust."

"We don't just want to be the tough chick who has no feelings, or the super girly girl who can't do anything for herself. We want that middle ground," she says.

With online word of mouth driving sales, fan gals have also started churning out their own stories about witches, vampires, wolves and half-bloods on such Web sites as http://www.textnovel.com under categories such as "Romance—Paranormal" and "Romance—Urban Fantasy."

"This is where the key demographic for the 'House of Night' lives, these teenage girls that are online most of the time," Matthew Shear, St. Martin's senior vice president of publishing, said.

Shear acknowledged Meyer's effect on Cast's series and other urban fantasy novels.

"We didn't buy the 'House of Night' series because of 'Twilight,' but when we saw sales increasing, we went to everywhere Stephenie Meyer was selling," he said. "Stephenie Meyer started the boom, and 'House of Night' has continued the boom."

He's cheering on sales.

"Is it welcome news to the publishing world? You bet it is," Shear said. "We're thrilled that people want to buy these books."