The Diablo 2 Wiki
The Diablo 2 Wiki archive is available for anyone looking for information on Diablo 2. All information here is pre-D2R but contains a lot of useful information that is still relevant. Updated sections for new D2R features can be found on the PureDiablo Diablo 2 section


From Diablo 2 Wiki

Undead, along with Animals and Demons are the three classifications of monsters found in Diablo II. Undead take 50% extra damage from blunt weapons, and can be resurrected by Greater Mummies. Monsters classified as Undead can be immune to Magic damage. However they are never immune to the paladin magic skills Holy Bolt, Blessed Hammer and the Holy Bolts that are emitted from a Fist of the Heavens attack.

See the Category:Undead for a full listing of undead monsters found in Diablo II.