Etsy seller BellaSmiles -- whose store is chock-a-block with delightful, gruesome desiderata -- is selling this lovely zombie wedding cake topper, perfect for your zombie wedding. We had a steampunk robot topper (natch!), but this would have been a strong contender.
Custom Zombie Wedding Cake Topper (Thanks, @bonniegrrl!)
Update: Candice sez, "I saw Cory's post about cake toppers and it reminded me of the robot cake topper my husband and I made for our wedding. It was a great collaborative project because it made us slow down and concentrate on something less volatile than, say, the seating chart in the weeks before the event. I highly recommend this kind of a project to any crafty folk out there about to get married -- or in the case of my husband, software engineers about to marry crafty folk."