Queller Demon

Queller demons  are a race of extraterrestrial demons featured in the television series Buffy the Vampire Slayer. They are known for occupying certain meteors, which they would hatch from after reaching earth. The species feeds on the insane and for that reason were often summoned in the middle ages to eliminate such individuals. The Character Ben summoned one to Sunnydale in 2000 to deal with the large number of mental patients. It was eventually killed by Buffy Summers when it targeted her mother.

Powers and abilities
Queller demons were able to adhere on flat surfaces such as walls and ceilings. They had the ability to track down the insane and to spit a gooey, alkaloid substance which they used to choke their victims to death.

Appearances
Buffy the Vampire Slayer -"Listening to Fear"