Paranormal cases probably shouldn't be included, but that's just my personal preference as in them they aren't thought of as undead, I think. For example, the ghosts in System Shock 2, Prey and BioShock are way different from what you'd understand undead to be. Closer to hallucinations, though not strictly speaking them either.

Commonly undead are limited to humans or the protagonist's own species (or to sentient species), so cases where this extends outside of them are interesting enough to know (e.g. animals and "monsters").