Modern zombies or Hollywood zombies, as portrayed in books, films, games, and haunted attractions, are quite different from both voodoo zombies and those of folklore. Modern zombies are typically depicted in popular culture as mindless, unfeeling monsters with a hunger for human flesh.
Modern zombies come in mobs and waves, seeking either flesh to eat or people to kill or infect. They are generally incapable of communication and show no signs of personality or rationality. Their collective and almost absurd presence (since they are dead) is closely tied to the idea of a Zombie Apocalypse the collapse of civilization caused by a vast plague of undead. The ideas are now so strongly linked that zombies are rarely depicted within any other contex.
These zombies usually originate from some kind of virus or ailment. A bite or scratch from a zombie can lead to death. Upon death the corpse reawakens as a zombie with a craving to feed on and kill other beings. There are usually immediate memory loss and personality change. Bodies remain functional as long as there is a connection to the brain and no significant brain damage, even when appendages are missing or not operable. Not all 'zombies' in this category are technically undead.
In some movies, zombies are portrayed as fast moving super-predators who seem to take on animal-like movements and hunting techniques. They sometimes run on all fours or sprint long distances until they have caught their prey. Sometimes they seem to go on the prowl in a zombie pack looking for people to devour. They can smell and hear you and there is no escape once one is on your trail.
Usually created by some sort of parasite, the human in question looses total control over his own body, which is hijacked by the host.
A parasite may it be alien or native can quickly spread within the population, controlling the decision centres and government officials. Such creatures can be found in Planet of Vampires or Ghosts of Mars.
Radiation has numerous effects on biological tissue such as causing brain damage, deformations, or even mutations of DNA. This could result in zombification depending on what effect the radiation has on the organism.
Types of zombies