|Voiced by||Peter Cullen|
John Guardian was Jessica Wray's uncle and a professional soldier. While in the army, John went on many dangerous and important missions and acted heroically. The day after he left the service, he visited Madame Why with Jessica to have his fortune told. Ominously, Madame Why predicted that John would soon begin the most important mission of his life and that he would never come back. This prediction didn't phase Guardian at all.
Almost immediately, John and Jessica were pulled into a mirror hanging in Madame Why's Wagon. Soon they were fighting off bug shaped robots called Invertroids. John picked up one of the robot's weapons, a Synchronizer that was able to send a person or robot into the Lost Dimension with a direct hit.
When the Ghostbusters joined John on the other side of the mirror, they helped him to find Jessica and free her and all the other human beings that had been pulled into their mirrors by the Invertroids.
The Invertroids were defeated and most of them were sucked into the Dimensional Gate and back to their home World. But because some of them managed to escape, John Guardian decided to stay in the mirror universe to protect the Earth from another Invertroid attack. He felt sure to find at least a few friends while exploring the dark side. He did however promise Jessica to come back to Earth for short visits.
John Guardian first appeared in the episode The Looking-Glass Warrior
Jessica Wray - His niece.