I've been thinking about the zombie types in Walking Dead. How they should be classified.
They have memory, coming back to old habits, hanging around the familiar. They know to use doorknobs to enter places. So these are smarter than average bears... er... zombies. Not smart zombies, but clever enough to occasionally stumble upon something clever that will throw a wrench into the protagonist's plans and assumption and thus advance the plot. "Whadaymean they figured out the 6 digit keypad combo at the secure perimeter?!!!!"
They're not Sprinters, and not Shamblors. They are something in between. They're Stumblers. Like drunk people. They aren't coordinated when they move but can put on a burst of speed when they need to.
If I may quote from Shaun of the Dead: "Just look at the face: it's vacant, with a hint of sadness. Like a drunk who's lost a bet." That characterizes the facial expressions of a standard Walking Dead zombie to a T. Er... Z.
So not really a new form, but a slight evolution of the classic Shamblor.