- "It's probably a mischief demon--Kelkor, or--"
- ―Jenny Calendar[src]
A mischief demon was a species or type of demon that could create annoying or harmful tricks. As Jenny Calendar assumed that a certain mischief demon was responsible for the activities of Moloch the Corruptor, it was implied that mischief demons were capable of creating power surges and on-line shutdowns, among other forms of mischief.
- "I Robot, You Jane" (Only mentioned)