Despite their penchant for shambling after us in murderous swarms, shedding body parts and converting us to the cause, zombies have clearly won our abiding affection. For several decades running now, zombie stories have been everywhere in popular culture, from film and TV to books and literature and even video games.

The AMC series "The Walking Dead" -- season four debuts this Sunday -- is just the latest example of a zombie story that has devoured our brains, culturally speaking. "The Walking Dead" regularly puts up rating numbers that are unprecedented in a basic cable series. In fact, last season the show's ratings among TV's prime demographic, age 18-49, were greater than any series on television, cable or network. While the show uses a zombie apocalypse as its premise, it's actually much more of a character-driven story that explores themes of society and morality.

In honor of the show's season premiere, we take a look at the specifics of zombiedom in "The Walking Dead," and explore the different kinds of zombies that have permeated pop culture over the years. Remember, citizens, knowledge is power. Know your zombies!

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Stalwart survivor Andrea (Laurie Holden) takes a "walker" for a walk in a scene from season three. AMC

For the uninitiated, "The Walking Dead" is based on comic book series of the same name, and depicts a group of survivors trying to find safety in the aftermath of a zombie apocalypse. The undead, called "walkers," are squarely in the tradition of pop-culture zombies -- the stumbling, the flesh-eating, the extremely poor personal hygiene....

But the cause of the zombie outbreak is still a mystery, and in a stunning Season Two reveal, it was disclosed that the survivors themselves carry a latent form of the zombie virus. In other words, when you die you get zombified, whether you were bitten or not.

Virus latency is a very real phenomenon, of course, and refers to viruses that lay dormant in the host for long periods of time without causing any symptoms or pathologies. The herpes simplex virus is one infamous example.

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Our hero Rick Grimes (Andrew Lincoln) contemplates the virtues of the chain link fence in a preview image from season four.AMC

The walkers in "The Walking Dead" are fairly standard-issue zombies, all things considered. In fact, depictions of zombies in science fiction and horror are pretty consistent. That's because the term "zombie" has traditionally been used to refer to a specific type of re-animated dead -- the mindless, ravenous walking corpse.

As such, zombies, like skeletons or ghouls, just don't have the narrative range of more sentient and sexy monsters, like vampires or werewolves. But if you dig around (heh) through the canon of zombie stories in movies, books, TV and videogames, you can find some interesting variations on the theme.

Historically speaking, stories of people returning from the grave, in one form or another, are as old as human civilization itself. References to ghosts, zombies and revenants -- in varying degrees of corporeality -- can be found all the way back to early Mesopotamian mythology.

Zombies on the run in the horror thriller "28 Days Later." 20th Century Fox

Released to theaters in 2002, director Danny Boyle's intense thriller "28 Days Later" was for many their first introduction to the idea of fast zombies. The baddies in the film are infected with the highly contagious "rage virus," which prompts extreme aggression and psychosis. The zombies here aren't technically undead, they're just infected, which presumably preserves the muscle tone required for running, sprinting and even swimming.

Examples of fast zombies can also be found in films like 2004's "Dawn of the Dead" remake and the recent film adaptation of "World War Z." Fast zombies work particularly well in video games such as "Left 4 Dead" series.

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Nicholas Hoult plays a soft-hearted and kinda cute zombie in the undead rom-com "Warm Bodies." Lionsgate

This year's cult hit movie "Warm Bodies" sounds like the worst kind of pop culture recycling -- the zombie apocalypse movie crossed with the romantic comedy. But it actually works well, thanks to Nicholas Hoult's performance as a sympathetic and lonely zombie named "R."

Plenty of other films have featured sympathetic zombies in lead or bit roles, like "Shaun of the Dead," "Colin" and even the recent kids movie "ParaNorman."

The dreaded zombie cat in a scene from the 1989 horror film "Pet Sematary" Paramount Pictures

Humans aren't the only species on the planet vulnerable to zombiedom. The concept of undead animals has been around forever, and is probably most famously depicted in Stephen King's very scary novel "Pet Sematery."

The film adaptation of that novel was a surprise hit in 1989 and a Halloween classic for an entire generation of kids who never looked at their pets the same way again.

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Deadly mushroom zombies attack in the videogame "The Last of Us."Sony Computer Entertainment

It's hard to wring anything new out of the zombie genre anymore, but the videogame "The Last of Us" -- a huge critical and commercial success this year -- managed the trick in a few different ways. The zombies in the game are actually infected with a kind of fungal virus that results in profoundly creepy man/mushroom hybrid monsters.

Interestingly, the game's very premise was inspired by real science. Game director Bruce Straley told Discovery News that the game was based partly on a BBC documentary, which detailed a fungal parasite that infects ants and alters their behavior.

Director George Romero reanimated the zombie story with his 1968 movie "Night of the Living Dead." Image Ten

Our contemporary conception of zombies as slow but monomaniacal brain eaters was more or less invented by director George Romero in his 1968 film "Night of the Living Dead." In fact, the term "Romero zombie" has come to represent a specific list of criteria that represents the modern zombie.

The film's sequel, "Dawn of the Dead," featured the idea that zombies return to the places they're most comfortable. In this case, the shopping mall. The scenario was seen as a wicked metaphor for mindless consumerism. The term "zombie" has since developed a connotation in the broader culture as a term for any kind of mindless automaton.

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The horror film "Dead Snow" is among several films and videogames to feature the scary idea of Nazi zombies. Storm Studios

The canon of zombie stories is littered with examples of hybrid beasties in which zombies are crossed with other kinds of monsters. The undead in author Richard Matheson's 1954 horror novel "I Am Legend," to cite an early example, depicts feral creatures that are essentially a cross between zombies and vampires.

Then you've got your demon zombies (Sam Raimi's "Evil Dead" movies), your alien zombies (the videogame series "Dead Space") and even the terrifying prospect of Nazi zombies, featured in horror films like "Dead Snow" and the "Call of Duty" videogame series. Everybody hates Nazi zombies.

Wes Craven's 1988 film "The Serpent and the Rainbow" was based on actual investigations of Haitian "zombie" rituals. Universal Pictures

The word zombie has intriguing roots in the real world. In certain West-African and Haitian religious traditions, a zombie -- or zombi -- is a dead person who is revived after burial and compelled to do the bidding of a sorcerer known as a bokor.

Some scholars believe that these kinds of zombies are quite real, though not undead. Instead, they're living people who may have been buried for a short period of time, then revived under the influence of powerful drugs cooked up by the bokor from plants, animals and even fish.