We all have a designer Zed that would have us peeing in our panties. I am a expert of my fears since I get regular visits of Night Terrors about zombies that leave huddled in a corner or in a frantic search for the gun while running for the attic.
I think I fear the most is just one zombie that was featured only once in Dawn of the Dead (remake). The buses had flipped over and a whole horde of those bastards were after them and this one female stops and stares into the camera. I've had several Night Terrors with that one little shot.