One of the worst things that can happen to a person is to be stripped of free will. Then again, if you are a zombie in either series you are dead. Aside from the fear of becoming one, possibly from a savage attack or just dying from some other cause, there's the fear of being surrounded by a dozen or more of them. They never sleep so you can never really rest. And someone is always dying so they never go away.
Zombies are a philosophical monster that symbolize the mysteries of life and death.
There's been plenty of zombie movies but the two most popular series are discussed here. The gos of material goods must have felt man went too far breaking the commandments of worshipping other icons. In Day we must have taken science too far. So we get punished by the gods with flesh eating zombies. The trilogy was set in Pennsylvania primarily except for Day which took place in Florida.