The walking dead that have only basic motor and mental function - their only purpose is to walk the earth in search of is food. Of course, we don't have to mention that their favorite meal is human flesh and blood. Here's how to put such an apoplectic costume together:
In the zombie world simply being undead isn't enough, and people need to see exactly how you died in the first place. Over the years, the trend with zombie movies has been to get more and more graphic, so you can serve as a perfect modern example of what this genre has become.
For this, you're going to need some latex prosthetics. These are fairly inexpensive for our purposes, and it's not hard to source a fake wound kit.
As with any zombie costume, give yourself a pale foundation that makes you appear dead, but this time add some gashes on your face and body. Have some fake blood dribbling from your wounds as well for added dramatic effect.
If you really want to get into it, you can also make some fake guts out of red play-doh or even rolled up strips of dyed paper and have them hanging out of your shirt. For your clothes, make sure that they are ripped and covered in blood. Besides that, just use your imagination. What kind of person were you before you joined the ranks of the undead?
If you want to pay homage to a certain time period such as, World War II, you might want to give the historical zombie costume a try. You can be an undead prince or lord from feudal times, or you can try your hand at being a zombie soldier that rose from the dead years after being gunned down.
If you're going with this option, follow the usual pattern of giving yourself a corpse-like makeup job, but be sure to make yourself look a little more decomposed. Add some clothes that are typical of the time period that you're going for, and make sure they look a little bit old and tattered.
This kind of costume goes especially well if you and your family are trying to keep to a particular theme. For example, if your theme is "the 1960's," you can be a zombie hippie or something similar.