An SD 1.5 model I trained on 30 of my favorite (most terrifying) Trevor Henderson creatures. I really like the result, and find most of what it creates pretty horrifying.

To prompt the model, use the keyword 'henderson creature'.
For example, 'photo of a henderson creature, house interior' will create a henderson creature lurking in a house, usually behind a doorway.
You can also combine it with other concepts, like 'photo of [character] lurking like a henderson creature, [location, additional descriptors]'
It's been specifically trained to respond to descriptors like interior/exterior, different locations, and descriptions of the creature, like 'humanoid' or 'crawling'.

I highly recommend adding the negative prompt 'bright, daytime, daylight' to make the images darker and creepier, and to encourage the model not to make the image daytime.

PS: The default civitai settings seem to make the generated images extra grainy/blurry. I don't think that's a bad thing, as it actually plays into the atmosphere quite nicely, but if you want to avoid that, you might want to tweak them, or just use AUTOMATIC1111's webui's default settings like I do.
Also, in case anybody wants to use my training data for their own purposes, I've uploaded it all here, including 1000 class images, and the unrefined source images.