Despite the fact that the modern zombie was introduced in 1968 by Romero in Night of the Living Dead it wasn't until 2006 and the publication of World War Z that there was a big, popular zombie novel (and even then I'm not sure it's that popular).
Whilst many of the big names in horror fiction have tried their hands at other "stock" monsters - vampires, werewolves, Frankenstein's monster, etc I'm not sure that any of them have done a zombie story. Whilst there are now lots of zombie novels out there they seem mainly to have been self-published or are at least by writers who've only written zombie fiction. Aside from World War Z the only piece of zombie fiction of real note is The Walking Dead which of course is very visual - I've always considered comic books to be half way between a novel and a movie.
Why is this? Why has mainstream horror fiction not grasped the zombie in the same way that the movie industry has? Does the fact that the big names in horror haven't written zombie stories indicate that they are hard or unsatisfying to write?
I can think of two things about zombies that make them more suited to movies than prose:
1) Gore is hard to write well:
Zombies are all about the gore. In a movie you can show a horrifically decayed zombie and it takes you a second. Similarly the death scenes work in movies because they're very visual. In prose to capture the same amount of gory detail you have to write a lot of words and the reader has to read a lot of words and that can end up feeling (for them) like a bit of a slog. Most importantly the volume of words slows things down. It gets in the way of the story.
2) Zombies are boring:
The very best horror fiction (for me) is about monsters that the reader can in some way sympathise with. It's tragedy. Think The Shining, Frankenstein, etc.
Failing that it's at least about monsters that are complex and interesting. Creatures or people that have some depth to them.
Zombies have none of this. They're entirely one dimensional, a faceless threat that could be replaced with any one of a number of other monsters - giant killer rats, aliens, whatever - anything that hunts in packs will do.
In all of zombie fiction and cinema I can think of only one zombie that had any character at all. The wonderful Bub in Romero's Day of the Dead manages to be sympathetic and actually get the viewer rooting and cheering for him. With that one exception zombies are entirely interchangeable and boring as characters.
I found both of the above to be true when writing my own zombie story Dear Suzanna. I got into writing a long graphic description of the first zombie the protagonist encounters and I enjoyed doing it but it definitely slows things down. So much so that when it came time for the first death I got it over with very quickly. The zombies in that story are all faceless threat with nothing more to them than that. They exist purely to drive the hero on to other actions. In some ways they could easily have been replaced by a flood or a fire or some other natural rather than supernatural threat.
So, zombies are boring. Agree?
'Dear Suzanna' is available for download from Smashwords or Amazon.