I dont even know where to begin with this one.
I went to a 'Witness' school so all through grade school I used to hear an unbelieveable amount of this nonsense. Especially around the 2nd and 3rd grade years did I hear tons of Smurf tales and the shit those evil little things used to do.
I dont know if it was just something that local parents came up with or not, but where I grew up we also had to be careful of ET. I dont know that it qualifies as demonic per se, but back when ET was popular there were these ET shirts that had a triangle on them. Kids were offically banned from wearing them to school because the death and resurection of ET in the movie had too much in common with Jesus and the triangle on the shirt certainly eluded to the trinity.
It kills me that I believed in the boogey man for as long as I did.