The walking dead, zombie land, I am legend, world war z. These are all popular media with on thing in common zombies. Zombies are a cultural phenomenon in sci fi movie books and tv shows. Most people write off zombies as make believe. But is there a possibility that it could one day become reality?
The idea of a zombie apocalypse is certainly one that, if given enough scientific evidence, could set the world into a frantic frenzy trying to prevent it.
As of right now there is no way humans can not come back from the dead. However there is a way we could see something like a zombie exist. It would be a virus similar to rabies, causing humans to behave like a zombie. Rabies causes death in the span of one week if not treated properly. However if the virus can change to avoid the body own natural immune system, then the way humans are affected could change as well.source
Also unlike all the movies I listed, rabies right now is not nearly as contagious. In order for a wide spread apocalypse, the virus would have to change to become airborne most likely.source
Another thing to think about is the fact that zombies already exist. Not like human zombies but zombie bugs and other creatures have this sort of thing in their species. New viruses are being formed constantly and there is no telling whether or not a zombie virus could pop up.source
So even though zombies could one day exist, it is very unlikely. However it’s still a good idea to stay away from rabid animals.