Zombies in Television:

Zombies are not usually the sole topic of a tv show, being more of an excuse to show the chaos that some unforseen disaster can throw into normal life. The Walking Dead, for example, has good, old-fashioned zombies, lurching around towns and cities and preying on survivors of some unknown plague. The cause of the zombie apocolypse is usually "unknown", but is down to some scientific tinkering. Some supernatural or science fiction shows will have the odd zombie-esque episode. Doctor Who is one example, in the episode "The Unquiet Dead". Other shows will feature zombies in a new way. In my personal favourite from France, Les Revenants/The Returned, the recently undead do not covert their friends' and family's brains, though they do have a terrific appetite. And they are able to walk and talk as though they were completely normal. The UK show, In The Flesh has the "partially deceased" returning to their old homes with all the problems that develop.

For more information see:
Wikepedia A list of 41 television shows that feature zombies.
Zombie Apocolypse: A good collection of articles about the zombie tropes, including "disappearing children" and "our zombies are different".