The Mirror Demon is a pale, skeletal, corpse-like man dressed in a black 19th century suit who was using the demons to make an army to take over the world. He also seems to enjoy inflicting pain on the possessed humans' spirits when they enter his world. His main goal is to replace all the human souls on Earth with his Ghostmakers. When the souls of Eduardo Rivera and Garrett Miller entered his domain, he planned to inflict the pain of death 1000 times over to them. When Slimer rammed the Mirror Demon in the head and split it open temporarily, Eduardo's soul escaped back to the physical plane. After Eduardo got his body back, he gambled that the Proton Streams would not reflect off the currently enchanted mirror. The Mirror Demon was torturing Garrett's soul when the beam hit him. He was pulled out of the mirror and was trapped, ending the threat of the Ghostmakers. Egon congratulated Eduardo for capturing the leader of the Ghostmakers.
The Mirror Demon is very evil and cruel, as he tends to torture the souls of his victims when they enter his world.
He can create an army of red demons to possess people. He is also capable of inflicting pain on the souls of those his minions possess. He even claims that he can inflict the pain of death a thousand times over through electrocution from his fingertips to increase suffering on the spirits of his victims.
- The Mirror Demon is the only ghost to have his head split open by Slimer.
- Garrett Miller (1997). Extreme Ghostbusters- The Ghostmakers (1997) (DVD ts. 09:42-09:45). Sony Pictures Home Entertainment. Garrett says: "These Mirror Demons keep us out of our body, right?"
- Mirror Demon (1997). Extreme Ghostbusters- The Ghostmakers (1997) (DVD ts. 04:05-04:22). Sony Pictures Home Entertainment. Mirror Demon says: "Comrade, the human realm will soon be ours. Join the others who have emerged and transform all mirrors into portals so we may continue to claim human bodies as our own. But first you must eliminate any threat impediments."