They are the darkest side of ourselves: brain-dead, devoid of emotion and built to kill - a terrifying glimpse of what happens when humanity loses its way.
Once, flesh-eating ghouls lived only in the fevered imaginings of sci-fi geeks and B-grade horror movie fans. Now, they are marching into the mainstream.
The resurgence of the zombie genre - led by the hit TV series The Walking Dead and movies such as World War Z and Warm Bodies - has become a global phenomenon.
And the fascination is not reserved for the screen. Entrepreneurs are cashing in on the surging popularity of the undead with large-scale role-playing games in warehouses decked out as monster-plagued medical facilities, and with interactive zombie running apps and zombie apocalypse survival courses.
In Melbourne, one company, zombiehire.com, is taking corporate team-building to the next level by releasing players into a ghoul-infested hedge maze in the dead of night until one uninfected survivor emerges as the winner.
There are even plans to turn downtown Detroit - a city decimated by the collapse of the US car industry - into the world's first zombie theme park, where day-trippers are chased through ''Z World'' by hungry hordes of the living dead.
But what does this insatiable appetite for rotting corpses say about us? Are we just fans of blood and gore who love to be petrified? Or is something more complex at play?
Pop-culture experts believe that beyond its escapism and entertainment appeal, the zombie genre attracts us by shining a light on our most challenging social issues and making us confront our deepest fears.
Just as George Romero's classic 1978 zombie movie Dawn of the Dead was seen as an allegorical statement on the horrors of the Vietnam War and the pitfalls of mindless consumerism, the new breed of zombie entertainment speaks to modern concerns.
''It's really tied into post-9/11 when a lot of the horror directors quite explicitly adapted the genre to reflect what's happening with the US and the war on terror, and media fear-mongering around ideas of invasion and your own country being taken over and your rights disappearing,'' says Angela Ndalianis, professor in screen and cultural studies at the University of Melbourne and author of the book The Horror Sensorium: Media and the Senses.
''The plot often involves experiments with the military and the government collaborating to create the zombie virus. So it's also the fear of where our science and where our technology is leading us to, and this critique of the methods used by government: surveillance, experimentation with genetics and biochemistry, and excessive military force.''
But it's not only Hollywood embracing the living dead. Last year, the United States Centres for Disease Control issued detailed advice on how to survive a zombie apocalypse as part of a government push to prepare the nation for a public health pandemic.
The disaster preparedness monthly online bulletin usually attracts about 1000 hits. The zombie edition received more than 26 million. It followed a 2012 military training exercise subsidised by the Department of Homeland Security, in which hundreds of military, law enforcement and medical personnel responded to a Hollywood-style zombie attack as part of their emergency response training.
The same year, Michigan State University offered a seven-week class in surviving the zombie apocalypse, in which students learnt about catastrophes and human behaviour by taking part in a simulated living dead outbreak.
But these are just examples of institutions using pop culture to deliver serious messages in an accessible way, right? It's not like a zombie plague could actually happen?
Matt Mogk - the world's leading expert on the undead, and founder of the Zombie Research Society - believes it's not so far-fetched.
''Zombies are not like vampires or mummies or other popular monsters; they're based in microbiology, not superstition and myth,'' he says from his home in Los Angeles. ''We have Harvard Medical School professors and leading neuroscientists from around the United States on our advisory board who have created a 3D scientific model of the zombie brain so they can actually model exactly what a zombie sickness would look like.''
Mogk, author of Everything You Ever Wanted to Know About Zombies, insists he's not unhinged or living in an underground bunker, and points to diseases such as rabies - which can create abnormal behavioural changes - as evidence that the truth is often stranger than fiction.
''If you said, is there anyone in the government actively getting ready for a zombie plague, the answer would be no. But if you ask, are you prepared for contingencies where there is a highly deadly infectious disease that causes people to turn into raving maniacs and attack each other and spread this infectious sickness, they would say yes, absolutely. There are too many weird diseases out there mutating in ways we don't understand to say that this couldn't be a possibility.''
While few might share Mogk's conviction, this end-of-days obsession is perhaps unsurprising when the world is grappling with increasing natural disasters, war, displacement and climate change.
Zombie culture is in part an exploration of the human condition, and how morality becomes a fluid concept when your species is facing extinction. How do you maintain your humanity if civilisation is collapsing around you?
Another consistent theme, according to Dr Lauren Rosewarne, an author, University of Melbourne academic and pop-culture commentator, is the way people perceived as a threat are dehumanised.
''In World War Z there are scenes where people are literally climbing over a wall to get into another country, and that's quite a metaphor for what will happen if our way of life is encroached upon by people we consider to be the 'other','' she says.
''Zombies are always in a state of physical disrepair - they're falling apart quite literally, and that level of desperation stirs something in us of fear but also the psychology of disgust. It's that dissonance thing where we can say, 'Well they're us but they're different.'
''That idea of them being constantly ravenous and hungry is that parable sense of what a lot of people see as resource-taking in the refugee or migration analogy.''
But for many zombie aficionados the appeal is more basic. It's just fun.
At university campuses across the world, young people are playing Humans vs Zombies, a game where students take sides and stage a week-long zombie war using Nerf guns. Here, the first event was at ANU in Canberra in 2009 and it has since spread throughout Australia.
Zombie shuffles in which the dead take to our cities regularly attract hundreds of participants who like to dress up and be corpse-like. And between October 2012 and January 2013, a crowd-sourcing campaign run by IRL Shooter saw more than 6000 people pay to take part in Patient Zero, a real-life zombie shoot-'em-up game using laser weapons in a Melbourne warehouse dressed up as an underground medical facility overrun with creatures of the night. A Sydney event planned for this year and run by the same company is expected to attract 10,000 players.
Jason Beks, founder of zombiehire.com - a Victorian company offering ''zombiegrams'' as a unique way to show a loved one you care, and walking dead actors for special occasions and corporate events - believes the popularity is about the thrill of being scared. He also stages ''Labyrinth Outbreak'' nights in which participants are chased through a maze by zombies.
''The reason we go to a horror movie is to experience fear, to get those fight-or-flight chemicals going,'' he says. ''Because the world's so safe and sanitised at the moment, we're so disengaged from real threats that we don't get to experience fear any more. So to create a scenario where there's real fear and real threat - people are queuing up for it.''
The good news, according to zombie guru Mogk, is that if the undead apocalypse is coming, we're in a good position to withstand it.
''We rated every country in the world with a population of over 5 million on what was the safest or least safe, looking at 20 categories, including climate, topography, military presence, gun ownership rate, disaster preparedness, public health infrastructure, and Australia was No.1 for surviving a zombie plague,'' he says.
''You have a low population density, you have a ton of land to escape to, albeit rugged land, and you have the world's largest moat around you.
''If the zombie plague were to start in Australia it would be a good thing for the rest of the world.
''If you ever wanted a good reason to move to Perth that's probably one right there.''