Zombies

Parent: (conditional ¹)
* Undead

Related:
* Undead menace
* Zombie apocalypse

Related: (causes)
* Parasites
* Infection / contagion
* Mind control
* Possession
* Magic
* Undeath - in settings where such is "natural".

¹) For example, creatures acting like zombies because of some mind-controlling parasite certainly aren't undead. Same for diseases, viruses, or other similar things that destroy higher brain functions and make people behave like zombies. Possibility of a virus that re-animates necrotic tissue is also vaguely possible. In all of these they're alive in terms of science but the original person is no longer there. Some zombie outbreaks don't even require the person to be dead to any degree and they simply become infected and instantly or slowly devolve into zombie like behavior as they also have become carriers of the disease.

These are either regular fantasy undead zombies, infectees of a zombie virus, or the sci-fi mutant zombies. So the games should be marked appropriately with the additional info (sci-fi, fantasy, undead tag, etc.). If in doubt, omit them.

Unlike skeletons, zombies still have muscles and nervous system and possibly brains to control the behaviour and therefore are not scientifically speaking dead. A somewhat common alternate interpretion for those that try to achieve a level of realism say they're infected with some strange virus or whatever that damages their higher brain functions, makes them ultra violent (hence the somewhat common name "rage virus"), and hungry for the flesh of non-infected. The undead kind that used to be popular were controlled by magic, demons, spirits, or some other external force to the corpse itself that could defy laws of nature.

Ultra violence and somewhat braindead (or rather rabid and animalistic) intelligence with the former personality largely destroyed are the defining traits. Though commonly they're also rotting alive, or suffer from effects similar to old scientifically inaccurate belief of how leprosy works (that is, body parts falling off).

Commonly highly contagious disease/virus that transmits via bodily fluids or open wounds.