Undead

Source Core Rulebook pg. 637
Once living, these creatures were infused after death with negative energy and soul-corrupting evil magic. When reduced to 0 Hit Points, an undead creature is destroyed. Undead creatures are damaged by positive energy, are healed by negative energy, and don’t benefit from healing effects.

Monsters

Aiudara Wraith, Banshee, Demilich, Devourer, Dragonscarred Dead, Dullahan, Elder Wyrmwraith, Forge-Spurned, Gashadokuro, Ghast, Ghost Commoner, Ghost Mage, Ghoul, Graveknight, Greater Shadow, Grim Reaper, Hellcrown, Lesser Death, Lich, Mummy Guardian, Mummy Pharaoh, Plague Zombie, Poltergeist, Remnant of Barzillai, Shadow, Skeletal Champion, Skeletal Giant, Skeletal Horse, Skeletal Hulk, Skeleton Guard, Skulltaker, Soulbound Ruin, Tzitzimitl, Vampire Count, Vampire Mastermind, Vampire Spawn, Warsworn, Wight, Wraith, Wyrmwraith, Zombie Brute, Zombie Hulk, Zombie Shambler