Harry Potter even annoys witches with its complete Godlessness - it is all about spells, and control of the environment in the complete absence of any Spirit or soul. It is totally materialistic. Whether it is demonic or not I don't know... If you want to read some really wonderful fantasy, try CS Lewis' fiction for adults, the Science Fiction. It is possible to write such fiction in a positive way.

I think a lot of Steven King in the past has been awful, but I must admit the Green Mile seemed to me to have a wonderfully Christian thread running through it. Okay, I wasn't Christian when I read it. I will probably read it again to see what I think now. But reading it as an athiest, it made me think about Jesus, and the sacrifices he made for us - so the Spirit can talk in strange places, don't you think?