The pile of bones suddenly stirs, rising up to take on a human shape. Its long, bony fingers reach out to claw at the living.
5e SRD
Mindless undead created to guard tombs or serve their creator
Skeletons are mindless undead created by an evil Magic-User or Cleric, generally to guard a tomb or treasure hoard, or to act as guards for their creator. They take only ½ damage from edged weapons, and only a single point from arrows, bolts or sling stones (plus any magical bonus). As with all undead, they can be Turned by a Cleric, and are immune to sleep, charm or hold magic. As they are mindless, no form of mind reading is of any use against them. Skeletons never fail morale, and thus always fight until destroyed.
Basic Fantasy Role-Playing Game
Skeletal remains of humanoids, reanimated as guardians by powerful magic-users or clerics. Often encountered in cemeteries, crypts, or other forlorn places.
OSE
Mindless undead created to guard tombs or serve their creator
These things are the result of an evil (or neutral at best) magic user or cleric wielding magics that animate the fleshless remains of humans, demi-humans, and various humanoids. They are completely mindless, only obeying the simple commands of their animator, which is often limited by the spell itself to a score of words. Some sages speak, though, of the mere proximity to great evil can animate the dead, resulting in armies of these horrors springing to unlife in forgotten catacombs and foul dungeons. Though given no commands, they seek out the living and attempt to force them into the ranks of the dead.
OSRIC