After gaming a bit this morning, I've got just a little rant about undead in more modern RPGs: What happened to undead being the stuff of nightmares? I'm not saying that it's all wrong, everywhere. I think there are some kinds of undead that seem to have held on to the long standing ideas.
Low-level corporal undead seem to be fine: Skeletons, Zombies, Mummies, Ghouls, etc. These range from weaker-than-NPC to stronger-than-NPC combat ability with the occasional nasty surprise like a disease or two.
High-level undead like Liches, Vampires, Death Knights, Revenants are often okay, but jus