Ok, just some more suggestions for any modeler looking for ideas:
First, Gargoyles. There aren't any Gargoyle models, which makes no sense at all. What eerie castle doesn't have creepy gargoyles all over the place? It's ridiculous.
Now this may sound weird, but in my opinion, the best gargoyles I've found are in Disney's Beauty and the Beast.
I'm not joking. I mean, look at these things. They're totally demonic:
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beautyandthebeast_1266.jpg (Size: 59.36 KB / Downloads: 172)
Second, serving carts. After all, a castle with servants should have one of those rolling cart thingys. Something like this:
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Although, it doesn't have to be nearly so detailed, and you could just have a cloth covering the whole thing, but the point is to have a rolling cart model that looks appropriate.
Lastly, it would be creepy to have a rocking chair. I mean, picture walking into a dark room and then a chair starts mysteriously rocking with nobody in it with those creepy creaking noises and then an eerie voice starts saying: "Norman... Norman..."