This season, television series are chock-full of creepy, crawly bugs, ghosts with some serious revenge issues, disturbingly creative serial attackers and aliens that do not come in peace.

"I don't think this is new," said Robert Singer, executive producer of "Supernatural" on WB. "I think people have been going to scary movies for as long as filmed entertainment has been on. And even before that with stage plays. It goes back to people telling ghost stories around a campfire."

Shaun Cassidy, executive producer and creator of "Invasion" on ABC, agreed. "Fairy tales help kids process their demons. Scary stories exist for adults for the same reason."

The stories that are unfolding on TV this season can be divided into three categories -- alien shows, paranormal programs and crime dramas (see story below). These and other scare-inducing shows follow some simple rules for success, including:

Using Comedy: Hurley on "Lost" is the epitome of this technique. On "CSI," Grissom is always dropping one-liners before investigating a crime, and the brothers on "Supernatural" make a sport of the fake names they throw around: "Star Wars" and the band Metallica were recent inspirations.

"Humor saves the day," Cassidy said. "Even in their darkest hour, people are funny."

But pacing is important when introducing a light note to dark situations. Singer likes to disarm his audience with humor and then hit them with a dose of horror.

"The only rule we have when our guys are faced with whatever the threat of the week is, [is that] we don't play the humor in the middle of those scenes," he said.

Providing Answers: The brains behind shows based in mystery know that eventually there has to be a payoff for the audience or a series can get tangled in its own mythology (see the final seasons of "The X Files").

"Lost," for example, kicked off this season by letting viewers know exactly what was in that blasted hatch. And on "Invasion," Cassidy promises that many of the questions posed in the pilot episode will be answered soon.

Greer Shephard, executive producer of FX's "Nip/Tuck" and TNT's "The Closer," pledged that the identity of the Carver -- the serial attacker in this season's "Nip/Tuck" -- will be revealed by the season's final episode.

AVOIDING OBVIOUS PLOTS: Playing with people's expectations and not succumbing to the cliches of the genre are part of the plan for many shows. "I think if we do subscribe to a convention of the genre, it's that we try to lull the audience into a sense of comfort and then spring [something horrific such as] the Carver on them," Shephard said.

But that's not to say the show writers avoid classic icons of horror.

"There's nothing wrong with doing a vampire story if it's a really cool vampire," Singer said. "Nothing wrong with a werewolf story if it's a really cool werewolf."

BASING IT IN REALITY: In "Supernatural," Singer said, "one thing that we try to do is to ground all this in some sort of legend -- something that, if you Googled it, you could find it." Take, for example, the Bloody Mary episode that explored the lore behind that creepy character.

Crime shows take a different approach. In "The Closer," Shephard said, "there are no monsters out there. When you go to investigate a crime you don't find paw prints, you find fingerprints. Which means all of this stuff comes from within human beings. The whole thrust behind our crime stories is that these are crimes that any one of us could have committed if we were pushed."

"Oftentimes the real life case is much worse than the one we actually portray," said Jennifer Finnigan, star of "Close to Home," a legal drama on CBS. "It's very eye-opening. The kind of shows we've done thus far are really intense and really shocking. And even scarier and more real because they are set in this really safe suburban setting."

Scare Tactics

Hollywood has gone beyond the standard-issue frights in trying to find new ways to scare viewers. Here are three areas in which the networks are raising the fear factor:

Paranormal Shows: The smash hits "Lost" and "Medium" spawned an outbreak of shows ("Night Stalker," "Ghost Whisperer," "Surface") that deal with monsters, demons, and the cranky undead. "I think people come to these stories willingly . . . because there's always that element of disbelief," said Robert Singer of "Supernatural." "Probably, it's more enjoyable to watch than a show about a terrorist because terrorists really do scare you . . . these kind of shows scare you in a way you want to be scared."

Crime Shows: Perhaps the scariest shows are the ones that are the most plausible. From "CSI" to "Crossing Jordan," episodic crime dramas remain TV's most popular format. "People like to be jolted out of the mundaneness of their lives," said Greer Shephard of FX's "Nip/Tuck" and TNT's "The Closer." "Many of our days are routine and ritualistic, and there's something to be said to being yanked out it for a second or two. It's a type of adrenaline rush. It's the same type of experience you have when you go on a roller coaster."

Alien Shows: Life-forms from other planets never seem to arrive wanting to eat at our restaurants, shop at our malls or read Us Weekly. Shows such as "Invasion," "Threshold" and "The 4400" all feature aliens that want to conquer society and mutate our genetic makeup. Even on "Smallville," Clark Kent is the only nice guy from Krypton. "It's the fear of the unknown," said "Invasion's" Shaun Cassidy. "We assume the enemy is smarter than us."

-- Amy Amatangelo