One of the most unique undead creatures are wraiths. The reason for this is because unlike zombies, wraiths sometimes just have astral forms or have their minds intact. Due to their distinct nature, wraiths cannot be killed like zombies and as a result do not have the same weaknesses. For my fantasy books, I am thinking of including combination between a wraith and a homunculus. A homunculus is the alchemical term for an artificially made being. Imagine an undead creature that is created through the use of alchemy. It gives me goosebumps!
Grady P Brown - Author 
Actually sounds like an interesting blends. I think blending (taking two concepts that have been done and putting them together to create something new) is one of my favorite techniques.