Zombies aren't slow and stupid.

Zombies aren't slow and stupid. Not always.

About a third of them are, as far as I can tell. Those are the "shamblers," who never tire and will always follow you, no matter where you flee, and how long you spend doing so. You know, the thing most people think of when they hear the word "zombie."

About as many are "stalkers." They're not any faster than they were in life (though not any slower either) and they tire about as easily, too. The thing is, they are capable of semi-independent thought, and retain most skills (but very few memories of events) they had before dying. This would include speech, but you can often tell their voices apart from those of the living simply because their tongues, lungs, and vocal cords have started rotting. Some particularly clever ones manage to prevent at least the appearance of decay by bathing in formaldehyde and the covering it up with various industrial-strength deodorizers. Of course, that requires access to those chemicals, which most of them don't have.

Finally, there are "chasers." They are fast. Faster than they were in life, in fact, but with only about the same amount of stamina, and recovering it in about the same amount of time. Much like the shamblers, though, they're basically dumb as bricks, so just locking all the doors and windows is enough to keep them at bay... as long as you get enough warning to do so.

In other news, thanks for inviting me over to share my documentation of my discoveries. Peer review is important, after all. I've spent the past few days giving lectures on the subject out loud to other, less-appreciative audiences, so forgive me if I don't talk much. Also, don't mind my pale skin and sunken eyes; long overnight research sessions tend to do that. Avoiding infection while studying the various types of zombie was challenging has been difficult, but luckily the lab has plenty of resources to decontaminate things.