HistoryAt the beginning of Last Action Zero, a Crater Critter is seen bathing in a volcanic crater, remarking that he would enjoy eating the brains of the locals once he is finished relaxing. Jenny and Brad interrupt his vacation, thus prompting him to battle with Jenny. Brad tries to contribute to the fight by tampering with Jenny's Net-o-Matic. This inadvertently hinders Jenny, allowing the Critter to trap the two. The Critter attempts to crack open Brad's skull, but is suddenly zapped by an ice blaster and frozen solid by a 7067 Skyhawk, along with the volcanic crater being frozen as well. The Crater Critter is arrested by the Skyway Patrol and taken to the ship.
After Brad is recruited by Skyway Patrol, a spaceship filled with Crater Critters arrives at the volcano. The rocky aliens blame Jenny for freezing it and ruining their vacation, and proceed to gang up and attack her. Jenny is badly injured and continues to fight the aliens, but the Critters are able to instantly regenerate their bodies after being harmed. They soon overpower Jenny and attempt to eat her brain, curious to see how a robot’s brain would taste.
The Skyway Patrol comes to the rescue yet again, but Brad is incapable of doing so due to the all of the excessive paperwork he is forced to fill out before carrying out any task. The Critter that was arrested at the beginning of the episode breaks free in the meantime. Jenny's metallic head is cut open, revealing her robotic brain as the Critters try to eat it, but they are immediately frozen by Brad and Jenny is rescued. Jenny and Brad battle the Critters by shooting paper at them — because rock is weak against paper (according to the Rock-Paper-Scissors game).
The Crater Critters do not make a return in the series afterward.