Scary history: Origins of 10 classic Halloween monsters

Ever wonder how come nonsensical creatures like men turned to wolves by moonlight or soulless, shuffling, brain-eating zombies were considered scary instead of silly? And scary enough that the tropes have survived for centuries? We dug into the history of 10 of our most enduring monsters, and unsurprisingly they often originate in attempts to explain the unknown or justify our deepest fears.

For example, when eastern Europeans in the Middle Ages noticed they were losing a lot of family members, it made sense at the time to blame the resurrected, life-sucking undead, according to Smithsonian Magazine. It's a myth that works without an understanding of germs and diseases like the plague and tuberculosis, which were what was really killing people.

Vampire bats were later named after the mythical monster and may even have contributed to the myth itself, according to one theory from a neurologist named Dr. Juan Gomez-Alonso. In addition to having a taste for blood, bats are known carriers of rabies, which can affect the brain and lead to myth-compatible things such as insomnia, hypersexuality and violent behavior.

Up next in vampire lore: the elusive vampire squirrel.

Before they doggedly shuffled, moaned and munched their way through countless breakfasts of brains to take up permanent residence in the hive mind of pop culture, zombies were originally animated in the minds of long-suffering slaves on the island of Hispaniola in what's now Haiti, according to an interesting history over at The Atlantic.

It was believed that slaves who sought to escape their bondage through suicide would actually find themselves trapped in their rotting corpse, forever cursed to haunt those they left behind. Over the centuries, and particularly in the decades since George Romero's movies helped make them mainstream, zombies have evolved into the ravenous, mindless monsters that continue to devour our brains today via a wide array of screens.

The image shows a zombie walk last year in Birmingham, England, to benefit a children's hospital. Hundreds of people participated.

Ghosts go waaay back, showing up in our oldest texts, myths, folk tales, hieroglyphics, you name it. Because they're a way of answering one of the fundamental questions of human existence (what happens after death?), they turn up pretty much everywhere, be it in photos from Mars or as 10-story-tall marshmallow monsters. We even have robots simulating ghosts today, which is the least of our concerns about robots.

The specter of killer robots has become almost fashionable to debate as we share roads with self-driving test cars, autopiloted Teslas and perhaps someday soon, SkyNet itself. But fear of machines turning against their makers goes back further than the Terminator franchise or HAL from "2001: A Space Odyssey."

You can find mention of warriors crafted from clay or metal in Greek mythology, for example, but the first real killer robots in the modern sense were "Rossum's Universal Robots" from the 1920 science fiction play "R.U.R." by the Czech playwright Karel Capek. The play's robots are really biological-mechanical hybrids, more like cyborgs or humanoid Cylons than straight-up robots, who nonetheless rebel against their masters and end up exterminating the human race.

R.U.R. went on to inspire future generations of science fiction. If you keep an eye out, you'll find plenty of references to Rossum and Capek in modern sci-fi works like "Star Trek" and even Joss Whedon's "Dollhouse."

Like the notion of ghosts, the idea of beings from beyond our planet has been around a very long time, as have people who believe aliens are real and visit us from time to time. But the archetypal short humanoid alien with gray skin and oversize head and eyes can be traced back to a 1947 incident in Roswell, New Mexico, and a faked alien autopsy video. Even before 1947, H.G. Wells described a race of moon men in his 1901 book "The First Men in the Moon" that matched the figure in the autopsy film...except Wells' aliens had stingers.

Mummies were the original zombies in a way. As is well known, mummification was a burial practice in ancient Egypt thousands of years ago, though it wasn't exclusive to the kingdoms along the Nile. What are believed to be some of the oldest mummies have been discovered in Chile, the product of ancient fishing communities.

As tales of the existence of ancient mummies spread to Europe and elsewhere during the age of exploration, the wrapped ones began making appearances in fantastical stories, according to LibraryPoint. That would've been as early as the 18th century, but we can really thank Bram Stoker and his 1904 novel "The Jewel of Seven Stars" for spreading the mummies-as-monsters meme.

From there, Boris Karloff first brought a mummy to life on the screen, and Hollywood has revived the trope every now and then ever since, though zombies are clearly doing a better job infiltrating our brains in recent years. Time to up that game, mummies!

The idea of wolfmen or werewolves goes back much further than you might think, to ancient Germanic pagan religious beliefs, according to LibraryPoint. The most ferocious warriors of the day were thought to be the wolves of the gods. As Christianity replaced older religious beliefs through the Middle Ages, stories of wolfmen remained a part of folk tales and accusations against real alleged werewolves persisted up until the late 19th century.

Werewolves arrived later to Hollywood than vampires and mummies, but the popularity of 1941's "The Wolf Man" cemented the trope and eventually gave us an awesome scene of a werewolf playing basketball and later, "Team Jacob."

What's up with the Grim Reaper anyway? Why is death so often portrayed as a skeleton in a robe with a scythe? Like some other modern monsters, we can trace this guy's origins back to a particularly dark time when scores of humans were being killed off by sickness for no apparent reason. We know now of course that the reason had to do with sanitation, bacteria and viruses.

According to a breakdown at How Stuff Works, the imagery of a skeleton in a black robe fits with traditional European associations of blackness with death and burial rites, and corpses and skeletons rotting in the streets were a common sight as the plague swept Europe (their less-than-speedy disposal probably helped spread the disease, too). The idea of reaping souls with a scythe, a tool used to harvest, also fits nicely into the imagery of the mostly agrarian society of the time. Some images show the reaper mowing down several people at a time with his scythe in a crowd, much as the plague was doing.

Witches, like werewolves, go way back in history. While the practice of witchcraft (or "wicca") persists in some capacity to this day, the role of witches in popular culture has long been that of the demonized outsider not to be trusted and perhaps to be feared.

The idea of witches as monsters of sorts is just as ancient and persistent as that of ghosts. They're just everywhere in our collective consciousness, seemingly back to the dawn of humanity.

But what's up with riding brooms? As it turns out, that's a totally NSFW origin story for another time. Let's just say it involves applying ointments to the nether regions. Not only were they allegedly evil scapegoats for just about everything, but witches were also slut-shamed throughout history.

When it comes to the archetype of the creepy clown, there are a few individuals that we can thank for the cultural popularity of the notion. The Atlantic argues it probably starts with the 1892 opera "Pagliacci" about a clown who commits murder, but it was John Wayne Gacy, a real-life serial killer and (quite successful) working clown that forever etched the killer clown notion into the collective consciousness.

From there, Stephen King's "It" certainly didn't help matters. As The Atlantic reports, Clown International has lost 90 percent of its members since the 1980s.

And so clowns may be on their way to becoming the latest unlikely cultural monsters that will persist through the decades. It makes you wonder if a viral video backlash is just over the horizon that will make cute cats and dogs the stars of our nightmares in decades to come.