Zombies are more popular than ever, but why? I know why I like them, because they freak me out; but why are they so popular on a global scale? There's been a lot of debate about this, but I think there's a couple reasons. One is that zombism is essentially a biological infection. It's not some magic spell, it's not based on ancient superstition or myth, so we understand it as a disease. We as a global society have a better understanding of microbiology and infectious diseases than we ever have throughout history. Zombies fit right in that mold with our understanding of infectious disease.
Another reason is that zombies are the only club that want all members. If you're a vampire and you're not cool enough, they'll kick you out if you don't wear the right pointy shoes or have the right ascot on. Zombies want everybody; they want the CEO, and they want the guy that works in the mailroom. They could not want you anymore than they possibly do, and they want the guy standing next to you, too. There's this notion of the spreading of zombies of everyone belonging, and you can see that in zombie pop culture, in zombie walks where anyone can come, and anyone is welcome.
Lastly, I would say that zombies more so than any other monster are synonymous with the end of the world. You never just see one zombie. 1 zombie equals 10 zombies, equals 10 million zombies. The aftermath of a zombie outbreak looks a lot like the aftermath of other major natural and manmade disasters that we're seeing on the news all the time. As we're more worried about the end of the world: Global warming, major economic collapse, major acts of terror, manmade or natural disasters; that fits right in the zombie wheel house. It makes zombies inherently feel real to us.