The Real Ghostbusters was always spooky show but it was a fun kind of spooky, like school haunted house. But on a handful of occasions the show became outright frightening and this episode was perhaps the most troubling. This episode, and its antagonist, actually scared me when I was younger. The idea of a monster that would knock on your window and attempt to draw you out had too much of a child abductor vibe to it for me to sleep soundly. Still to this day, when I hear a creak in my house, I wonder if the Grundel is near.
Special Thanks to Ghostbusters Animated for use
"A boy named Lee goes to the Ghostbusters for help when his brother, Alec, begins acting strangely and doing bad things. When the guys decide to investigate, Egon learns a Grundel is making Alec do bad things and if something is not done soon, he will become one".