An undead is a once-living creature animated by spiritual or supernatural forces. See Table: Undead for physical ability scores, recommended minimum Hit Dice, and damage based on size.
Hit Die: d12.
Base Attack Bonus: 1/2 of total Hit Dice (see Table: Creature Saves and Base Attack Bonuses).
Good Saving Throws: Will.
Skill Points: 3 x Int score, plus 2 points per Hit Dice beyond 1 HD.
Undead share the following additional traits.
Weapon and Armor Proficiency: Undead receive either Archaic Weapons Proficiency or Simple Weapons Proficiency as a bonus feat. An undead is proficient with its natural weapons and any weapon mentioned in its entry. Undead noted for wearing armor gain the bonus feat Armor Proficiency with whatever type of armor they are accustomed to wearing (light, medium, heavy), as well as all lighter types.
Immunities: Undead are immune to poison, sleep, paralysis, stunning, disease, necromantic effects, and mind-affecting effects. They are not subject to critical hits, nonlethal damage, ability damage, ability drain, energy drain, or effects of massive damage, or any effect requiring a Fortitude save unless the effect also works on objects or is harmless.
Healing: Undead cannot heal damage on their own if they have no Intelligence score. Undead can be healed with negative energy (usually only available through the use of magic). Most undead are destroyed immediately if reduced to 0 hit points or less.
Special: Undead cannot be raised from the dead.