Slug is the paternal entity in a trio of ghosts. They appear to originate from New Jersey, according to the P.K.E. Meter readings taken while they haunted a Conrad's chocolate plant.  The Ghostbusters eventually captured them after a lengthy bust, but they escaped from the Containment Unit. Slug desired revenge and set up a fake paranormal eliminations and investigation business to bankrupt the Ghostbusters.
As his scheme began to pay off, Slug decided to escalate things and seek out an old friend named Turlock. They arrived at an abandoned toy factory in Brooklyn, a known dwelling of Turlock. Instead, Slug awoke and angered a Free Roaming Vapor that turned out to be a Full Magnitude Class 10. It pursued Slug and his family across the Brooklyn Bridge. The Ghostbusters recaptured them and then focused on the Class 10. Slug and the family were later part of the entities that witnessed the arrival of Egon Spengler into the Containment Unit universe when he was in search of the Ghost of Christmas Future, Ghost of Christmas Past, and Ghost of Christmas Present.
Slug has a nasty temper.
Shapeshifting: Slug can change his appearance.
Flight: Slug can fly, just like any other ghost.
Invisibility: He is shown to be appear out of thin air.
- While he isn't the same as the Little Hopper Ghost (most noticeable is the spikes from the head to lower back), he also appears on some merchandise as did some season 1 and 2 ghosts.
- In "Standing Room Only", his design can be seen multiple times (sometimes in the same crowd shots) and like many ghosts in that episode are used as stock ghosts.
- On page 15 of Ghostbusters Issue #1, Slug makes a non-canon cameo as the apartment superintendent.
- Slug makes a cameo on a special sketch cover of Ghostbusters #9.
- On page nine of Ghostbusters Volume 2 Issue #20, Slug makes a non-canon cameo in the last panel on the left in his disguise.
- On page 31 of Ghostbusters Annual 2018, in panel 1, a ghost is based on Slug.
- ↑ Slug (2009). The Real Ghostbusters- Ghosts R Us (1986) (DVD ts. 15:00-15:02). Time Life Entertainment. Slug says: "It's me! Slug!"
- ↑ Egon Spengler (2009). The Real Ghostbusters- "Ghosts R Us" (1986) (DVD ts. 2:40-2:41). Time Life Entertainment. Egon says: "Possibly New Jersey."
- ↑ Egon Spengler (2009). The Real Ghostbusters- "Ghosts R Us" (1986) (DVD ts. 2:32-2:35). Time Life Entertainment. Egon says: "We have three Class 5 Full Torso Apparitions."