Happy October, everyone! In the spirit of the Halloween season, I’ll be writing about classic horror monsters all month. At least once a week, I’ll post about a classic monster and the deeper psychosocial fears underlying it. This week, we’re starting with a modern pop culture favorite: zombies.

Shambling, moaning, and craving human flesh, zombies have been a staple of pop culture for decades. It’s hard to pinpoint the first appearance of zombies in our collective imagination. Reanimated corpses have been a mythology trope across multiple civilizations for centuries. Aside from possibly Jesus, the earliest zombie I’ve been able to find comes from Lucan’s Civil War (completed around 65 CE) which depicts the witch Erichtho briefly resurrecting a dead soldier so he can foretell Pompey’s future. Other than being dead, this decomposing fortunetelling Roman bears little resemblance to today’s zombies, which take more cues from Haitian voodoo. Dead bodies revived to serve as soulless slaves, the voodoo zombies exhibit the mindlessness we associate with modern zombies, but there’s a uniquely American contribution to the zombie mythos: the horde.

While so many of the traditional horror monsters are outcasts and loners, zombies are unique in that they always travel in a massive horde. An individual zombie wouldn’t present much of a threat, but as their numbers increase, zombies become a force of nature. You don’t stop a zombie outbreak; you can only survive one. And your chances for survival depend on the people around you.

And hey, speaking of your “zombie survival party,” have you ever noticed how, in zombie stories, the true villains are almost never the zombies themselves? 28 Days Later, the George Romero films, the Walking Dead— all of them use zombies to raise the stakes, but the ultimate conflicts are always between still-living people. In almost all modern media where zombies appear, squabbles between humans lead to the zombies’ slow inevitable triumph, and this only adds to their terror. In a “zombie apocalypse” scenario, the more we fight amongst ourselves, the more likely we are to be bitten and become part of the mindless horde.

And therein lies the real terror of zombies: at the end of it all, maybe we’re part of a mindless horde already. Maybe individualism is a lie, and our society is really just a thronging mass of humanity spiraling toward inevitable self-destruction and meaninglessness. To become a zombie is to lose our distinctiveness as we devolve into mindless wanderers stoked only by the drive to consume. Zombies represent the traumatic end of uniqueness and the deep-seeded fear that we don’t actually matter. They invite the terrifying question: What if we’re all just mindless consumers already?

That’s why zombies are scary.

If you’d like to discuss zombies further, Brew Theology recently did a two-part podcast on zombies and the fear of meaninglessness. Click here to check it out. And make sure to check back next week for another installment of “What Makes It Scary?”