The Furnace Monster  is an entity taking the appearance of a furnace.
The Furnace Monster manifested when the Ghostbusters attempted to escape from Wat's house. Its form is that of a black furnace with glowing red eyes and a fiery inner core for its mouth. Winston Zeddemore quickly told Ray Stantz to drop his trap into the Furnace Monster's mouth. The Furnace Monster swallowed the trap and immediately imploded. The blast propelled the Ghostbusters outside of the house.
- In previous scripts, Peter suggested an "Ecto-Grenade" to blow the monster up with. 
- ↑ Rader, Brad (2009). The Real Ghostbusters Complete Collection Volume One Disc Five, "Mrs. Roger's Neighborhood" Storyboard p. 133. CPT Holdings, Inc. Line reads: "Furnace Monster crawls up epiglottus towards cam, breathing..."
- ↑ Rader, Brad (2009). The Real Ghostbusters Complete Collection Volume One Disc Five, "Mrs. Roger's Neighborhood" Storyboard p. 134. CPT Holdings, Inc. Peter says: "Drop the Ecto Grenade down it or something!"