D&D General Favorite Creepy Monster To Run?

[Benjamin Olson]

It's lore and stat block doesn't really have much to support this so far as I know, but I always felt a Nightwalker that freely slipped between the shadowfell and the prime material plane, or that visited people's dreams, or that only certain people could see, or that could just appear and disappear as the scene demanded, would make for a great horror one shot. Basically if they followed supernatural horror movie monster tropes rather D&D monster tropes I think they've got a great look and vibe for it.

 

[Deset Gled]

I think rot grubs are probably the worst, because most of the others have workarounds, like fire or listening to doors using a metal cone with a screen on it.

The only way to not get rot grubs is to not loot bodies.

"Ha ha, suckers, you should have known better to, um, look for treasure!"

I think the Rust Monster is also pretty high on the list.

I just sent one at my party last week.

 

[Brendan Byrd]

That was the very good advice given in the Ravenloft Monstrous Compendium volumes: Describe them, don't name them. Even the most mundane D&D monsters can be terrifying, given this treatment. (I believe TSR used an ogre in their example, and it wasn't even a creepy Pathfinder ogre, but it was still was quite effective.)

...and then ploink chess pieces down with a "Sorry, I don't have minatures for these yet, so this will have to do for today."
Also an opportunity for a skill check to identify...pass or fail, the player gets a note with a name on it...