It's Oct. 31, and Halloween fanatics everywhere are probably engrossing themselves in a marathon of scary movies, filled with monsters like the Wolfman, zombies, and Count Dracula, among others. But one scientist has recently debunked the myth of these movie monsters with science, saying that they actually originated from a poor understanding of certain diseases.

Medical maladies such as porphyria, which affects the skin and nervous system, rabies, and hypertrichosis - the excessive growth of unwanted hair - have all inspired these beasts.

Take Dracula, for instance, most noted for his pearly white fangs, pale white skin, and thirst for blood. His appearance most closely matches with the disorder porphyria, the symptoms of which include sensitivity to sunlight, insomnia, and skin redness, which might make the skin look bloody.

"In the 10th or 11th century, Romanians at the time often didn't bury their dead in very deep graves," Greg McDonald, director of forensic medicine at Philadelphia College of Osteopathic Medicine, said in a press release. "Sometimes, the bodies would shift."

"So imagine you're a peasant," he continued, "and you come across a body that is pale and looks like it has blood around the mouth. You might think he'd been walking around, feasting on the blood of others."

Count Dracula's thirst for blood may seem scary in the movies, but according to McDonald porphyria is to blame for the myth that perpetuated the idea of vampires.

Porphyria, WebMD says, is caused by a problem in the production of heme - a component of hemoglobin, which is used to carry oxygen to red blood cells. There are various type of porphyria, but most of them are inherited. About half of them occur when one altered gene is passed down from just one parent.

Dracula, based on Bram Stoker's penned famous novel from 1897, isn't the only monster that is misunderstood. Zombies, which movies tell us are the result of some lab experiment or disease gone wrong, in actuality are simply inspired by strung-out individuals on drugs and people working the graveyard shift.

Then there is the manic, crazed-looking Wolfman, who only comes out with the full moon and, supposedly due to the condition hypertrichosis, is covered head to toe in hair. But the poor Wolfman is not only plagued by fur-like hair, but also rabies, causing him to pant excessively and foam at the mouth.

Rabies, the Centers for Disease Control and Prevention reports, is a preventable viral disease most often caused by the bite of a rabid animal, such as a raccoon, dog or bat. Other symptoms include fever, weakness and general discomfort. But as the disease progresses, more severe symptoms will develop like partial paralysis, insomnia, hallucinations and confusion.

It appears Hollywood exploited yet another illness to create movie monsters of epic proportions.

And with this "forensics of famous movie monsters" in mind, McDonald believes such horror film characters might not be so scary after all - they're just sick.