Zombies awaken a fear of the darker more savage part of our nature. What scares most people is to think that all it takes is one bite to turn a normal cognitive person into a drooling growling flesh-hungry zombie. Also, if the zombies themselves were not scary enough, seeing the survivors can bring unease. In a world where the dead walk, is it ok to dig deep into your darkest desires and take that TV? If you're stealing a TV what makes rape so bad? What about murder. That jackass just looked at your TV wrong and you've had no sleep. Is it really that bad to accidentally let your pistol go off in his face? That would leave his poor wife widowed, but thats fine with you, because you know that you can be there to comfort her, whether she likes it or not.

There are a lot of different factors to just how scary or creepy zombies can be. Every romero movie has both the obvious external struggle with the walking dead, as well as every character having an internal struggle with themselves to find out who they really are. Good, or Evil.