Catching the wave of a public fascination with vampires, HBO's "True Blood" has steadily increased in stature to become the cable network's most popular series since "The Sopranos" and "Sex and the City."

Based on the series of bestselling Sookie Stackhouse novels, written by Charlaine Harris and starring Anna Paquin in the lead character's role, "True Blood" has grown its Sunday night viewership by 66 percent since its debut in September.

The first season finale airs this Sunday, with a second season already in production.

"True Blood" casually imagines a world where vampires, telepathic women and "shape shifters" — people who can assume the shapes of animals — are a part of everyday life in a small Louisiana town. A steamy romance between Paquin's waitress and Bill the brooding vampire, portrayed by Stephen Moyer, stands at the show's center.

Alan Ball, who produced HBO's "Six Feet Under," kept the foreboding darkness expected in vampire stories, spiced up the sex and violence, mixed in humor and explored the theme of outsiders in society, he said.

The novels are centered on Stackhouse; but Ball said he had to develop some of the characters around her to avoid overworking Paquin.

The fictional genre of women and their supernatural beaus was something new to Ball. Surfing some chat rooms, he's noticed that many women are connecting to the story of Sookie and Bill.

The series averages 6.8 million viewers each week. As is typical for HBO, the viewership is scattered around in-demand viewing and reruns aired at different times during the week. But Lombardo said he's noticed that more people are tuning in for the Sunday episode premieres, a sign of anticipation among fans.

The series started quietly and has built its audience week-to-week, Lombardo said. Even notable successes like "The Sopranos" grew more slowly, with a big jump coming at the start of the second season, he said.

The series will return for its second season next summer, and HBO is looking to build anticipation by releasing a DVD of the first season before that.