Lauren Cohan rudely encounters a title character from âThe Walking Dead.â  TELEVISION, long the home of monstrous behavior, has never seemed like the ideal medium for actual monsters. TV has tried to generate chills over the years, but for every occasional success like “The Twilight Zone” or “The X-Files,” there’s a “Kolchak: The Night Stalker” or “666 Park Avenue” that was quickly killed off. If you’re looking for legitimate, jump-from-your-chair scares, the conventional wisdom goes, you’re usually better off in a theater.  Lately, though, horror has stormed the small screen, winning over viewers in large numbers by rewriting the rules specifically for the medium.  “The Walking Dead,” which returns Feb. 10 to AMC, is already one of television’s most popular dramas, and “American Horror Story” is finishing up its second season on FX with a third on the way. Fox has a serial killer series, “The Following,” starting its body count on Monday, and coming soon are the Jekyll and Hyde-inspired “Do No Harm” on NBC and “Cult” on CW. Meanwhile “The Vampire Diaries” (CW), “Grimm” (NBC), “True Blood” (HBO), “Supernatural” (CW) and “Being Human” (Syfy) continue to scare up decent ratings.  “Now there shouldn’t be any doubt that TV can be as frightening as feature films,” said David Schulner, executive producer of “Do No Harm,” which follows a kindly Philadelphia doctor by day who becomes a violent psychopath by night.  That’s not an easy accomplishment. At the cineplex the setting seems more ideal: a dark room filled with strangers. At home, however, the lights are on, and you’re sitting in the same place where you laughed at last week’s “Modern Family.”  But Mr. Schulner argued there’s actually “no place scarier” for a frightfest. “When I’m home, everything I love is near me,” he said. “So the slightest creak or noise outside while watching something designed to frighten you is the scariest thing.”  Just as characters in horror films must deal with the frequent appearance of unwanted entities, so too must horror shows confront something equally unreal that makes their job more difficult.  “My frustration is with the thing that keeps network television alive: the advertisements,” said Kevin Williamson, an executive producer of “The Following,” which he created, and “The Vampire Diaries,” and the screenwriter of “Scream.” “It’s very difficult to create any suspense if you’re riding into a commercial break every few minutes. The ads take you out of the moment, so you’re always writing a big moment for the act break, and God forbid if the audience doesn’t come back after it. That’s a luxury shows have on HBO or Showtime, but I haven’t had on a network.”  However, even pay-cable shows seldom have the time and money to develop the effects-heavy mayhem of even the average creature feature, which means TV producers must be more creative in developing their monsters. “We never go into an episode thinking we’re going to outdo some big horror movie,” said Jeremy Carver, executive producer of “Supernatural.” “What’s worked for us over the years is to not just show monsters, but also find monstrous things about creatures you might not associate with being scary.”  So while there are vampires and werewolves in “Supernatural,” there’s also been a satanic Santa Claus and a killer angel. Twisting expectations like this “isn’t necessarily going to create the same edge-of-seat horror experience you get in a movie theater,” Mr. Carver added, but it does allow for a sense of unpredictability.  For Mr. Williamson less gore on TV means more suspense: “Everyone keeps asking me about the scary, the scary.” His show has been cited in the post-Newtown debate about violence in entertainment. “But all I’m thinking about when writing is the love story, the love story. I don’t try to add murders for the sake of murders, because that can take away their meaning.”  To Mr. Schulner seeing a monster leap out or a head chopped off is “the release of tension” rather than the cause of it. That’s why he has paid attention to making his Hyde “sexy, devious and dangerous.” When the character seduces a woman in a hotel room, he creates the longer-lasting feeling of suspense than just a quick chill.
Horror series are multiplying on television, with âDo No Harmâ and âThe Followingâ among the latest, but the medium imposes special challenges for creators.