I knew a JW lady who claimed that a necklace she bought at a yard sale was possessed. It gave her nightmares and stuff started moving around her apartment. She was known to have mental issues so I don't think anyone else really believed her.
Another older JW lady claimed to have been attacked by a demon. She blamed it on her husband having an affair and that allowed the demon into their home. Never heard THAT theory before. She said she called out 'Jehovah' and the demon ran. Wimpy demon!