A Hop Jack is the Ghouled version of the Hop Rock. These Ghouls are gray, and have brown backs with yellow bulbs. The Hop Jack also comes in a blue and red-coloured form, which is stronger than the brown and yellow version. At 100mph, they emit a high pitched screech, and become a sickly yellow, with a blue, spiky helmet.
- Protoform Abilities - Firecrackers.
- Skizzler - Sizzles as it flies, producing a medium-sized explosion.
- Blastfield - Lays small sparking balls as a proximity mine field - an opponent's first trip causes a chain reaction.
- Shrieknel - Explodes in front of an opponent- one large explosion followed by multiple smaller blasts.
- Blastrap - Morphs into smaller balls to form a floating explosive minefield around an opponent.
- The World Beneath Our Feet Part 1 (First appearance)
- The Trade
- The Slugout
- The Slug Run
- Shadows and Light
- Mario Bravado
- The Journey Home
- The Unbeatable Master
- What Lies Beneath
- The Return
- King of Sling
- Keys to the Kingdom
- Back to Blakk
- Bandoleer of Brothers
- Dark as Night
- Light as Day
- Slugterra: Ghoul from Beyond
- Slugterra: Return of the Elementals
- Slugterra: Eastern Caverns
- Second Chances
- Get Pronto
- Eastern Tech
- Slug Day
- The Fall of the Eastern Champion (Appears in flashback(s))
- The Lady and the Sword
- The Emperor Strikes Back
- The Return of the Eastern Champion
- Slugterra: Into the Shadows
- This is the only Ghoul to have a complete design change in season 2.
- Hop Jacks looks a lot like Greneaters.
- Hop Jacks were almost the only ghoul used in Season 1.