An early version of Brad Pitt's World War Z held the potential to be a "genre-defining" zombie movie, which sadly didn't prove to be the case. Given how ubiquitous the undead are in popular culture now, it's hard to imagine a period where there were almost no zombie movies or TV shows to speak of. The success of the Resident Evil games in the '90s eventually led to movies like 28 Days Later or the Dawn of the Dead remake, and suddenly zombies were everywhere. Amidst this resurrection of the undead came Max Brooks' World War Z, a sprawling novel depicting humanity's fight against hordes of zombies.
https://screenrant.com/world-war-z-movie-change-zombie-genre-what-happened/