A Class 8 entity is a special classification for very powerful extradimensional beings and used once but not in the primary canon.
Primary Canon
No entities have been classified a Class 8.
Secondary Canon
Ghostbusters: The Video Game
List of Entities
Ghostbusters: The Board Game
List of Entities
Animated Series Class 8
The animated series doesn't follow the same rules as RPG and can go higher. To read more about it go to Animated Classifications.