I feel like skeletons have kinda lost their luster in a lot of games, but I couldn’t quite put my finger on why. They’re often used as obvious tableau monsters–skeletons at a table playing cards? They’ll get up and attack you; skeletons laying down in beds? They’ll get up and attack you. At one hit die and easily turned by priests, they just never seem like that big a threat unless they can get economy of action on you. And even then, they’re often mundane mooks; players aren’t really scared of them. Then I remembered…
Skeletons are supposed to REEEEEEEEEEEE!
None of the games I’ve been in have done this, and I’ll admit I’ve failed to include it myself. But when skeletons attack, they are supposed to shriek for up to three rounds. And during each of those three rounds, there’s a 50/50 chance that a wandering monster will come check out what the hell is going on.
So, you go from a blah encounter with a few skellies that the clerics turn and the fighters hack to bits to a cascading nightmare as the dungeon’s alarm system has just alerted half the dungeon to your presence.
Edit: Oops! Looks like I screwed this up! The picture for skeletons are under the entry for Shriekers. No wonder! But hell, why not have skeleton shriekers?