The Zombie, as an archetype, is perhaps the most socio-political monster of them all. It says, in effect, “Your neighbors want to kill you, so maybe you should kill them first.” Although its many cultural incarnations all reflect the universal fear of dead, the last 150 years have seen this archetypal monster  assume forms that seem especially relevant to the modern/ post modern era.
(“BRAIIIIIIINS!” From Return of the Living Dead, the source of the whole “zombies eat brains” thing.)
Until the 1800s, the Vampire archetypes of early legends were essentially zombies: shambling, rotting dead folks who had returned to prey upon the living. As with the later zombies, these undead critters reflected the fear that Death would utterly consume Life, usually before Life was ready to die. Shortly after the turn of the 19th century, however, the Romantics and Decadents (most notably John Polidori and Sheridan LeFanu ) turned that archetype into a charming but voracious member of the gentry, thus remaking the Euro-American vampire into what eventually became the familiar “Dracula” Vampire archetype.
Originating in the West African slave-cultures of the Caribbean, Brazil, and the United States, the traditional Zombie archetype first represented the most horrible things imaginable to both a slave-people (the idea that you could be forced to work even after death) and their “owners” (the idea that your slaves could rise up en mass and you could not stop them). Essentially a Yoruban vampire-myth mixed with the horrors of racial slavery , this created a “new” archetype for a “new world.” For obvious reasons, that zombi/ Zombie carried a racial overtone that has, over the last few years, become a class-based overtone instead.
In the 1950s, zombies became “pod-people,” representing the fear of fanatics from, and conversion to, a fearsome ideology. Whether that ideology was Communism, McCarthyism, or something else  was up to the individual to decide, but the archetype still resonated with the fear that your friends and neighbors would soon turn on you.
In the late ’60s, George Romero and John Russo created – accidentally – the “ultimate consumer”: the cannibal dead. Although they claim they had not intended that subtext when they made Night of the Living Dead, the filmmakers’ “ghouls” captured the socio-economic fears of Vietnam-era America – fears that catalyzed roughly 10 years later (after the Ghoul archetype had merged with the Zombie and the Pod-Person) in Dawn of the Dead (1978) and Return of the Living Dead (1985), which made the whole “They’re coming to get you” theme of the original film even more explicitly consumerist. 
A spate of European zombie films – mostly Italian and Spanish knock-offs of Night of the Living Dead and Dawn of the Dead – brought back the old theme of vengeful. corrupted corpses. In many cases, though – especially in the Spanish Blind Dead series (1971-75), Lucio Fulci‘s Zombie and The Gates of Hell (1979-80), and the French film The Living Dead Girl (1982) – those zombies reflected the growing divide between pre-WWII “Old Europe” and the raging insecurities and hormones of the “new Europe” emerging during and after the 1960s. Generally, these Euro-Zombies were relics of Old Europe literally feeding upon New Europe. That feeding could be affectionate, even tragic (see The Living Dead Girl), but the results remained the same: Your loved ones, or your past, are gonna consume your ass.
(The genuinely tragic climax of La Morte Vivante, aka The Living Dead Girl.)
Since then, the Bush-era socio-economic paranoia has made the Zombie into the ultimate symbol of social collapse. The fact that the archetype now also carries the gleeful murder of your fellow citizens (“They’re dead – they’re all messed up” ) as a kicker says all kinds of unnerving things about the global attitude of the current era. The “dead” might be fast, might think, might not even be physically dead; still, they would stalk you, consume you, and turn you into one of them if you don’t kill them first.
(The perfect socio-media satire, Shaun of the Dead.)
As the new millennium grinds toward its third decade, the Zombie archetype seems tired yet far from dead. And although recent manifestations have injected more obvious humor, surivalism, and socio-political satire into works like Shaun of the Dead (2004) or Pride and Prejudice With Zombies (2009), that monstrous archetype’s base anxiety – that we are one step from being consumed by our neighbors – seems as resonant as, if not more resonant than, it has ever been before.
1. The Latin roots of the word “monster” reflect both omen and revelation: “…‘monstrum’, from monere (to warn) or monstrare (to exhibit) — and was in principle the equivalent of the Greek teras, meaning sign or warning. The ‘monsters’ of the classical world were thus those signs, not necessarily of human or animal origin, that were clearly identifiable as such, and teratology, the science that studied those signs, was simply a different form of divination. It must be emphasized that it was precisely because of their unusualness that monsters were defined as being clear and distinguishable warnings...” http://www.answers.com/topic/monsters-1#ixzz30IGOC8Bq
2. Polidori’s novel The Vampyre (1819) was conceived during the same weekend ghost-story contest that birthed Mary Wollstonecraft Godwin Shelly’s classic Frankenstein. Both books (and monsters) were created at the behest of Lord George Byron, and Polidori’s
novel about “Lord Ruthven” was originally credited to Byron by the book’s first publisher. Neither Byron nor Polidori was especially happy about that, especially since Lord Ruthven was a barely concealed caricature of Byron himself, and of the “Byronic antihero” that Byron’s work established. We can both credit and blame Polidori, then, for the endless parade of suave and angsty vampires that have populated our media ever since.
Le Fanu’s contribution, Carmilla (1872), brought us the seductive “vamp,” in the form of a Sapphic noblewoman with irresistible beauty, charisma and appetites. Carmilla, however, is more like a classical faerie temptress than a walking corpse. Both Ruthven and Carmilla predate Stoker’s Dracula (1897) by several decades, and both clearly influence this most famous vampire.
3. Initially based in the soul-duelist beliefs of Yoruba slaves, the zombi is said to have originated with the fear that Baron Samedi – Loa of the Dead – would refuse to collect your soul if you had offended him. With your soul divided, you would be prey to people who could imprison part of your soul in the rotting remains of your flesh, and thus keep you enslaved long after you were supposed to have died. A worse fate, especially for a slave, is difficult to imagine.
4. The 1978 remake replaced political paranoia with the social paranoia of mindless conformity and sudden aggression – both of which were timely fears for the vapid, violent 1970s.
5. In the years between Night of the Living Dead and Dawn of the Dead, Russo and Romero had a falling-out. The resulting court cases left both men with the rights to make sequels to their film by splitting elements of the title, Romero getting “dead” and Russo getting “living dead.” Both films changed the Zombie archetype in significant ways.
6. A line from the original Night of the Living Dead.
(The Frankenstein of zombie novels, Seanan McGuire’s classic Feed (published under the name Mira Grant.)