Undead are Creatures who should rightfully be dead, but have cheated fate and remain unnaturally alive. Some died and returned, others avoided death by unnatural means. Many are cursed and want to escape their undead existence. Most are vil and seek to destroy life, but many have some kind of honor or code, and some are actually wise and good.
Limitations: Supernatural Creature, Undead, Unliving.
Almost all undead have DamageImmunity: Life
Ghosts
Hhosts are Spirits, who have returned to the land of the living. They need not be spectral creatures, some appear fully material. But they are all extradimensional creatures who should rightfully have departed this world, but were bound here or drawn back by some power or passion.
Mummies
Some people strive for immortality by preparing their bodies for death. Liches and mummies are the most common types. These undead usually have some degree of control over their undead existence, and most chose to be this way. They thus have less problems with unlife than others.
Vampires
Vampirism is a plague spread by Corruption. The living are infected and return as unliving parodies of themselves.
Walking Dead
Some corpses return to a semblance of life. These are generally unwilling undead, and either strive for rest or are merely malicious.