You should also know, however, that most of these characters have medical and psychological "baggage," say the handful of experts who study them.
So don't just take along a vial of blood or some magic potion to make your character more believable. Find out the possible medical and psychological reasons that may have made them so frightening in the first place. But beware: Even the experts disagree on the truth surrounding some of the creepiest Halloween characters.
Halloween Character Case File No. 1: Witches
Witches got a mostly bad rap as sinister types who cast spells in the Middle Ages, says Stanley Krippner, Ph.D., professor of psychology at the Saybrook Graduate School in San Francisco. And it's typically undeserved, he insists. They may be the most psychologically healthy of all the creepy Halloween characters. "In the Middle Ages, some of the witches were probably emotionally disturbed," he tells WebMD. "But in my opinion, most of them were not. They were very good herbalists and midwives. Some of them were surgeons.
"Remember, this was an era where women didn't have much power," Krippner says of the witches' heyday in the Middle Ages. "This was one way they could get some respect."
Some witches, he suspects, were better doctors than the men doing the healing back in those days. But as the witches got more powerful, buying up land wanted by the men, he says the anti-witch crusades occurred, including the witch hunts of the 14th century.
Not all the witches back in the Middle Ages were on that level, of course, Krippner says. "As with any profession, there probably were a few kooks."
Likewise, Krippner says, modern-day witches, by and large, are "a very positive, respectful, peaceful religious group."
Halloween Character Case File No. 2: Zombies
Zombies could be considered innocent bystanders, just the guy or gal next door -- until someone in the villages of yore decided they had done something wrong. "They then would go to a trial by ordeal," says James D. Adams, PhD, associate professor of pharmacology and pharmaceutical sciences at the University of Southern California School of Pharmacy, Los Angeles, and an expert in zombie history.
Townspeople would rub a preparation of Datura stramonium on their bellies, Adams says. "The Datura stramonium contains scopolamine, the motion sickness drug," Adams says. The belief was that if people were innocent they wouldn't have any symptoms from the preparation being rubbed into them.
But people absorb it at different rates, he says. "The people who react quickly absorb scopolamine within a couple of hours," Adams says. "In some, scopolamine can take 13 hours to be absorbed."
Those who absorb the preparation quickly can begin to hallucinate, with visual and auditory changes, and their breathing becomes depressed, he says. Those are the ones who turn into "zombies" -- someone who can barely walk, barley see, and walks very clumsily. They walk around with arms outstretched, stiff arms and legs, as if they are bumping into things, he says.
Those who absorbed it slowly, he says, went home and slept it off. And they were presumed innocent.
Another expert, Daniel Lapin, PhD, a clinical psychologist with a private practice in San Francisco, sees the medical mystery of zombies differently. In Haiti in the 1700 and 1800s, the bokor, or priest, selected a victim and laced his drink with curare, a preparation of plant poisons that knocks out the motor nerves but keeps the sensory system untouched.
"As total paralysis sets in, the bokor pretends to be magically inducing the paralysis," Lapin says. "The bokor next officiates at the victim's burial. The victim thinks he or she is being buried alive." And the victim is right.
Two or three days later, the bokor digs up the victim. "The victim bonds subserviently and forever with the person who digs them up, usually the person who drugged them," Lapin says.
Sometimes, however, Lapin says the victim would "go crazy during the ordeal," and the bokor then has no use for them and drives them away. The victim would then be likely to wander from village to village, Lapin tells WebMD, earning the reputation as the village idiot.
Halloween Character Case File No. 3: Ghouls
Ghouls, traced back to ancient Arabic folklore, have a complicated, troubling psychological profile. They like to hang around burial grounds. And they have an obsessive-compulsive desire to consume corpses, says Lapin. "Unlike a psychotic, they know what they are doing, know the consequences, know it is wrong, and could turn themselves in," he says.
"Some just obsess about this in their head," he says, but some actually do the dastardly deed. In 19th-century India, for instance, Lapin says there are reports of women with this condition, sitting around a grave and "chowing down."
Halloween Character Case File No. 4: Vampires
Probably the best-known vampire is Dracula, the centuries-old vampire who stars in the 1897 Gothic horror novel by Bram Stoker.
While some say vampires have no heart, that's not true, says Lapin, who self-published a book, The Vampire, Dracula, and Incest. "A vampire has a heart, but it is imploded [psychologically]," he says. That's the origin, he says, of a vampire's need to suck blood.