Reflections are the main antagonists of the Goosebumps book Let's Get Invisible!. One evil reflection also appears in the More & More Tales to Give You Goosebumps short story Mirror Mirror on the Wall.
Let's Get Invisible!
Max Thompson met them in the mirror in his attic, the mirror could turn Max, his brother Lefty and his friends invisible, but what they didn't know is that inside is a demon that wants to trade places, Max's reflection almost succeeded, but Max escaped just in time. In the end, Lefty's reflection escaped as well, because he was using his right hand (Lefty is left handed).
Mirror Mirror on the Wall
Bonnie Sue Bowers says that she is the most pretty girl in the world, but not anymore, and it is all because of her reflection! Bonnie's reflection came right out of the mirror and tried to shove the real Bonnie Sue into the mirror. Bonnie smashes the mirror though and it shatters into a thousand pieces. From the shards rise more and more Bonnies, she then takes out her compact mirror in her pocket and it sucks up all of the miniature Bonnies. A few days after that, Bonnie goes to try out hairstyles in the mirror. But she is pulled inside and traded with her reflection. So now she spends her time waiting for a chance to escape, especially since Reflection Bonnie does not take care of herself and dresses like a slob!
In Goosebumps: The Game, you encounter a reflection that is inside a mirror while in the attic of the Dead House. A book in your Dad's study refers to the monster as a "Mirror Demon". The player can defeat it by smashing the mirror with a hand mirror. If you attempt to smash the mirror too quickly, the reflection will kill you. Once you successfully break the mirror, you will recieve the achievement, "I Was your Evil Twin", referencing the book I Am Your Evil Twin.
- Is revealed in Mirror Mirror on the Wall that The Reflections can multiply themselves from shards if their mirror is broken.