The Monster is, hence its name, an aggressive green creature who once attacked the castle, and was eventually attacked by the army. It made its debut and was the main antagonist of The Monster (Blooper). The Monster also appeared as a cameo in The Adventure through Time, where Jacob accidentally traveled to the past time when the military nuked the castle.
- The Monster was mentioned by Jacob in Dylan and Kazi's Extravagant Adventure, although it never appeared itself.
- The Monster has never actually appeared, but instead only his roars indicate his presence.
- In the ending of The Monster, military transmissions are audible. In the final one, the transmission is cut-off mid sentence as a large growl is heard, indicating that the nuclear blast was unsuccessful in destroying the creature.