A zombie is essentially a reanimated human There are many types of zombies all of which belong to the world of science fiction (for now). More specifically, one can classify them into 3 basic types of zombies.
When you watch Resident Evil, zombies are exactly what you expect them to be. Creatures that used to be human until they were infected by a virus, which turned basically into living dead. The infected person seems to lose its human-like character traits soon after the infection, he stops being self-conscious and stops being able to effectively communicate with others (even if they are zombies too), and basically turn into bloodthirsty creatures that seek to tear apart human flesh. Killing them is always difficult, since they are already dead. Their flesh is rotten, and any wounds they sustain won’t easily put a halt to their vicious attack. It can, however, slow hem down, which will probably give you enough time to escape. If you really want to take such a zombie down, the best thing you can do is to aim for the head. Empty your gun on the creature or, even better, chop its head off with a sharp blade. The rest of his body parts will continue to move erratically for while, pretty much like a headless cockroach, but ultimately the creature will die (for the second time).
Except for virus infected zombies, the realm of magic and the realm of cybernetics have their own types of zombies to represent them in fantasy literature. A dark magic zombie is a dead creature that has been reanimated with the help of dark magic thanks to a spell that is cast by a powerful wizard. Wizards that have the power to control dead bodies are called necromancers. Despite the fact that they have no control over their body, dark magic zombies are somewhat intelligent since they are guided by a sentient being (namely the necromancer). That is why they are also far more dangerous than virus infected zombies. If you want to get rid of a dark magic zombie, the best thing you can do is to either break the spell using your own kind of magic, or to kill the necromancer controlling the zombie.
Last but not least, the cybernetic zombie is by far the most technologically advanced and probably most dangerous among the three types of zombies. As the name suggests, a cybernetic zombie is a dead corpse that has been reanimated with the help of cybernetics, and nanotechnology. A cybernetic zombie should not be confused with a cyborg. The cyborg differs from the cybernetic zombie in two important ways: the first is that a cyborg is basically a living person that uses high-tech devices in order to sustain life and to enhance his capabilities, while the cybernetic zombie is brought back to life thanks to technology. The second and most important difference, however, is that the cyborg is still a person that has control over his body and has the ability to reason also, while the zombie is fully controlled by some sort of artificial intelligence.
In conclusion, different types of zombies bring different things to the table and offer the reader (or viewer) a different reading (or viewing) experience. The only thing that remains to be seen is what types of zombies does the future of sci-fi have in store for us?