The Pyro-Hippo Ghost was a ghost the Ghostbusters failed to capture. It was later vaporized by Robo-Buster, but became part of the Spectral Mass. In the end, it was trapped along with the other ghosts that formed the ectoplasmic amalgamation.
The Pyro Hippo Ghost manifested in the 42nd Street New York Subway rapid transit station for the IRT Lexington Avenue Line 4 and 5 trains. This entity had the power to breath fire from its mouth. During the bust, the ghost melted the Ghostbusters' Neutrona Wands, forcing them to retreat. Robo-Buster arrived on-scene. Being fire-proof, it vaporized the ghost quickly and easily. The ghost then became part of the Spectral Mass that manifested and tried to get revenge on Paul Smart. During the Ghostbusters battle with it at Grossjuck Plaza, they trapped every ghost, except Slimer, that made up the mass, including this Pyro Hippo Ghost.
- In the "Robo-Buster" script, the entity was generically referred to as "fire demon." 
- ↑ Moss, Francis (2009). The Real Ghostbusters Complete Collection Volume Four Disc Five, "Robo-Buster" Script p. 22. CPT Holdings, Inc. Line reads: "As the Fire Demon blasts again, the Ghostbusters head for cover, just ahead of the flames, diving behind trash receptacles, support columns, anything handy."