Tobin's Spirit Guide is the in-universe reference work the Ghostbusters consult to identify the ghosts, spirits, demons, and other entities they encounter. Egon Spengler and Ray Stantz lean on it so often that they appear to have whole sections memorized. This part of the GBFans.com wiki is organized around it: every entity the team has faced across the films, cartoons, comics, and games has its own catalog entry, and they are gathered into one browsable index below.
The ghost class system
The Ghostbusters sort entities using a primary seven level classification system, running from Class 1 up to Class 7. A common misconception is that the number measures raw power. It does not. The classes are based on a mix of factors, including an entity's appearance, its sense of its own identity, and its effect on the surrounding environment, so a clever Class 4 can briefly outmatch a higher number under the right conditions. A full rundown of the system was published in the comic Ghostbusters 101 #1.
- Class 1 is a low powered manifestation that lacks the psychokinetic mass to affect the physical world. These entities fade in and out of the physical plane and are often described as not yet fully developed, echoes of feeling rather than personalities. They produce localized cold spots, unexplained lights or sounds, and the occasional faint telekinetic contact.
- Class 2 has a slightly firmer grip on the physical plane than a Class 1 but still does not fully manifest. Its defining trait is the ability to possess inanimate objects for a longer continuous stretch of time.
- Class 3 is humanoid and shows general, purposeful behavior. Its form ranges from a body almost indistinguishable from a living person to a distorted mockery of humanity with exaggerated features. The constant is that a Class 3 does not know its own identity, sometimes not even to itself. A Class 3 that learns who it was will either move on to the next plane or resist that pull more fiercely.
- Class 4 also has a human form but, unlike a Class 3, it knows its identity and carries memories, or copies of memories, from its past life. Resolving a Class 4 case often means researching that person's life, their wants, habits, and obsessions. Given a power source to draw on, such as the River of Slime or the ambient energy Gozer gathered before a manifestation, a Class 4 can briefly wield power on the order of a Class 6 or Class 7.
- Class 5 is a fully formed manifestation, most often the by-product of highly charged emotions and ambient psychokinetic energy. It can have human touches such as limbs or a face, but its overall form is non-human and it tends to lack personality or intelligence. Slimer is the franchise's signature Class 5: famously tagged on screen as "a focused, non-terminal repeating phantasm, or a Class 5 full roaming vapor."
- Class 6 manifests in forms and behaviors that are entirely animal in nature. It matches the appetites and instincts of its living counterpart and can appear at wildly different sizes.
- Class 7 is the most powerful class, covering godlike beings, demons, and other overwhelming manifestations. They can communicate with humans and are not wholly alien in their desires, emotions, and origins, which makes them no less dangerous. Class 7 entities are to be avoided, and luck is often the only thing that gets a team through an encounter. Gozer and Zuul sit here.
Several video and tabletop games, including the realistic version of Ghostbusters: The Video Game, Ghostbusters: Spirits Unleashed, and Ghostbusters: The Board Game, extend the scale with Class 8 and Class 9 entries for their most extreme threats.
Alongside the numbered class, an entry is often tagged with descriptive prefixes that capture how an entity behaves rather than how strong it is. Common ones include Focused (bound to the place it first appeared), Free Roaming or Free Floating (moves at will), Repeater (returns on a cycle until its source is disabled), Anchored (tied to a location), Animator (can inhabit or move objects), Vapor (an insubstantial haunting), and Caustic (corrosive or otherwise harmful). The Library Ghost, for example, is recorded in Tobin's Spirit Guide as an anchored Class 4.