Like the Mummy, Zombies are a lumbering, staggering, Halloween and Horror presence.
What makes zombies different is that they do not come from a European gothic tradition. Instead, the zombie story originates in Haiti, where West Africans were brought as slaves to work on the sugar plantations.
As a part of the voodoo religion, Haitians believe that magicians, or houngans, can revive the recently dead, turning them into mindless, soulless servants. Believers in voodoo will guard the grave of deceased relatives until they are certain that it has begun to decay, for the magic only works on fresh bodies.
Today, scientists have studied the zombie legend and have developed several of explanations for the belief. Victims of a number of psychiatric disorders such as catatonic schizophrenia may exhibit symptoms that could be wrongly interpreted by the superstitious as zombies.
Another explanation suggests that the houngans may have used combinations of toxic drugs to send their victims into a deep coma. Mistaken for dead, the victims would be buried, only to be disinterred and revived by the Houngan. Other drugs would be used to keep the "zombie in a passive and obedient state.
As with much of the horror mythology, the Hollywood version is the one we most recognize. The first zombie movie may well have been the 1932 Bela Lugosi film, White Zombie. In it, Lugosi plays a zombie master who orders his creatures to kidnap a woman with whom he has fallen in love. The woman is rescued by her husband, who throws Lugosi over a cliff. The zombies, faithful lemmings that they are, follow him to their own (second) deaths.
In 1968, George Romero re-imagined the zombie in his low-budget film, Night of the Living Dead. In the Romero films - and, indeed, in most subsequent zombie films - the dead are a sort of plague, spreading beyond control. In Night, they are resurrected by a nuclear spill (another great modern fear), and go in search of human flesh to eat. It's quite a change from the original voodoo concept.
The zombies in the more recent 28 Days Later are the result of a biological disaster, as a germ kept in a laboratory is let loose by animal rights terrorists.
Biological contamination and nuclear radiation are both real modern fears. A lot of people don't believe in vampires and werewolves anymore. But nuclear accidents and biohazards are real possibilities.