Just what is a scary movie? Why do they frighten us and why do so many of us find that so thrilling? The hour-long documentary “Bloodsucking Cinema” (7 p.m., Starz) takes an enthusiastic look at the vampire in film from the silent classic “Nosferatu” by German expressionist director F.W. Murnau to contemporary versions of the genre, including “Underworld: Evolution,” “BloodRayne” and “Van Helsing.”

Richard Roeper hosts and narrates this survey, stuffed to the bat rafters with interviews and clips. Director Joel Schumacher happily discusses the cult that has grown up around “The Lost Boys,” a film that many doubted because of its combination of horror and humor. John Landis recalls “Innocent Blood,” one of his more forgotten films, which also combined dark humor, vampirism and overt eroticism.

Too much of “Bloodsucking Cinema” seems devoted to special effects and the toys of big-budget filmmaking. Too many directors and technicians tell us that computer software and prosthetics have helped them “improve” on their horror influences. But time will tell if films like “BloodRayne” or “Prince Of Darkness” will be remembered like the Universal films of the 1930s or the Hammer horror movies from the 1960s and 1970s.

Cheech Marin offers some fun observations about the evolution of the Mexican vampire genre and how directors Quentin Tarantino and Robert Rodriguez adapted the gory tradition in their over-the-top opus “From Dusk Till Dawn.”

¢ Often slick horror, software-generated effects and buckets of money can’t buy a thrill. Sometimes the cheapest movies are the scariest. And for my money, one of the creepiest movies ever made has to be “Carnival of Souls” (1 a.m. Saturday, TCM), a 1962 shocker made for roughly $30,000 by director Herk Harvey, of Lawrence, Kan., a maker of industrial-training films.

Unknown actress Candace Hilligoss plays a church organist who apparently survives a car crash only to be haunted when she tries to move away from rural Kansas. Don’t dare miss this. Set your TiVo/VCR/DVR or stay up real late and watch this in the dark!

“Carnival” was quickly consigned to TV repeats in the wee hours. The film was rereleased to critical fanfare in the early 1990s, when director Harvey was saluted as a pioneer independent filmmaker. Michael Weldon, author of “The Psychotronic Encyclopedia of Film,” gives “Carnival” top honors and considers it “required viewing.”

¢ Many contend that our excitement at horror provides a fleeting diversion from deeper misgivings about mortality. As one expert in “Bloodsucking Cinema” opines, vampire films offer a grim and terrible vision of an empty immortality to make us feel more resigned to our own short spans.

Speaking of all that – death comes to yet another major character on “Meerkat Manor” (7:30 p.m., Animal Planet). Just weeks after Flower’s passing, “Meerkat Manor” viewers will have to sit vigil for another anthropomorphized critter.

Tonight’s other highlights

¢ Halloween unfolds rather badly on “Ghost Whisperer” (7 p.m., CBS).

¢ The top 12 pop combos clash on “The Next Great American Band” (7 p.m., Fox).

¢ A teen vampire targets Internet escorts on “Moonlight” (8 p.m., CBS).

¢ Taylor mulls a life-changing move on “Friday Night Lights” (8 p.m., NBC).

¢ The teenage daughter of a victim inspires Jill on “The Women’s Murder Club” (8 p.m., ABC).

¢ An apparent Robin Hood may turn out to be just a hood on “Numb3rs” (9 p.m., CBS).

¢ A rogue ship seizes Sheppard on “Stargate: Atlantis” (9 p.m., Sci Fi).