Apocalypse: Could a fungal infection turn us all into zombies?
Let me introduce you to something really terrifying: a fungus that turns its victims into zombies.
Its spores (reproductive cells) enter the body, then the fungus grows and begins hijacking the mind of its host until it loses control.
The parasitic fungus devours its victim from the inside, extracting all the nutrients from it, while preparing for the big end. Then, in a scene more disturbing than any horror film, it explodes, spreading its spores on everything in the place, and exterminating the others with the same fate as zombies.