The Metamorph is a large, grotesque, shape-shifting entity that could change into just about anything.
A week before encountering Drool, the goblin in the Poconos sideshow, the Ghostbusters had a run in with a spirit which Ray Stantz called a Free-Floating Miasmic Phantom, whom at first was a phantom and then changed into a carnivorous vacuum cleaner, who according to Peter Venkman, gave him some nasty scars that still linger. The Ghostbusters failed to capture him.    
After their first run in with Drool and then being sent away by Madame LaFarge they are attacked by an electrical wire that snaps loose from a telephone pole. The Ghostbusters are convinced more or less by Venkman that Drool was behind the attack. After getting into a town to fix the Ecto-1, several incidents happen to the Ghostbusters until they are finally confronted with the true enemy. Later on, it is confirmed to be the same miasmic phantom that escaped the Ghostbusters a week earlier. Drool sacrificed himself to distract this phantom and allow the Ghostbusters to trap it. In doing so, Drool saved the lives of the sideshow people whom had given him a home.
In November 1997, Egon referred to it as a Class 4 Shape Shifter. 
- In The Real Ghostbusters' "The Grundel", the Metamorph is briefly seen in an entry Egon flips past while researching the Grundel.
- On page 18 of Ghostbusters: Get Real Issue #1, on the white board, in the middle left of Chi-You's photo, is a photo of the Metamorph's cockroach form later used in Ghostbusters Volume 2 Issue #12.
- On page 11 of Ghostbusters: Get Real Issue #3, the photo of the cockroach form as depicted in Volume 2 Issue #12 appears in the middle of the whiteboard, left of Chi-You's photo.
- "Drool, the Dog Faced Goblin"
- "The Grundel"
- Egon briefly flips past its entry in Tobin's Spirit Guide
- "Back in the Saddle, Part 1"
- Mentioned by Egon
- ↑ Ray Stantz (2009). The Real Ghostbusters- Drool, the Dog Faced Goblin (1987) (DVD ts. 16:29-16:32). Time Life Entertainment. Ray says: "It's kinda like that Free Floating Miasmic Phantom we never could catch."
- ↑ Peter Venkman (2009). The Real Ghostbusters- Drool, the Dog Faced Goblin (1987) (DVD ts. 16:36-16:40). Time Life Entertainment. Peter says: "First, he was a phantom. Then, he was a carnivorous vacuum cleaner. I still got the scars."
- ↑ Ray Stantz (2009). The Real Ghostbusters- Drool, the Dog Faced Goblin (1987) (DVD ts. 16:45-16:46). Time Life Entertainment. Ray says: "Too bad he got away."
- ↑ Winston Zeddemore (2009). The Real Ghostbusters- Drool, the Dog Faced Goblin (1987) (DVD ts. 19:07-19:10). Time Life Entertainment. Winston says: "The Shape-Changer that got away last week!"
- ↑ Egon Spengler (2009). The Real Ghostbusters- Drool, the Dog Faced Goblin (1987) (DVD ts. 13:56-14:02). Time Life Entertainment. Egon says: "What we're dealing with here is a Non-Amalgamated Shape-Changer. It can attack in any form"
- ↑ Egon Spengler (1997). Extreme Ghostbusters- Back in the Saddle, Part 1 (1997) (DVD ts. 07:16-07:19). Sony Pictures Home Entertainment. Egon says: "Reminiscent of the time we busted that Class 4 Shape Shifter in the Poconos."