Gargoyles

I haven't ever encountered one but I have heard that they are protector or guardian spirits, with decent power

How an entity looks in the astral plane could mean anything though. The astral plane doesn't have the same rules as the physical so visual appearances aren't always relevant to what it actually is. Visual appearances on the astral plane are just a visual presentation of how it sees it's self.

Some people in real life put gargoyles on buildings to protect them

gargoyles are known to fend off evil and be like a guardian of sorts, they probably would get aggressive should u ever come near them (the place they guarding)

I readthat gargoyles are put on churches/cathedrals to scare away demons. That's all I know about them.