Green Ghoul is a one-time character in The Thundermans. He appeared in the first Halloween special, Haunted Thundermans. He is a ghost that was once imprisoned by Hank Thunderman, but escaped after Miles and Louie accidentally freed him.
He took control of Phoebe and almost killed Hank, but was foiled by Max. He battled the Thundermans and Hathaways and was defeated when Phoebe and Max combined their ice breaths and Hank threw him into the Ghost Cage.
Green Ghoul once attempted to take over the world. He almost sucseeded but was stopped by Hank. When in ghost jail, he was freed when Louie made a crack in the wall. In order to get revenge on Hank, Green Ghoul possesses Chad to get close to Phobe. Eventually, Max realized that he was the Green Ghoul with his ghost-tracking device, but Phobe didn't believe him. After he possesses Phobe, Max tried to fight him off, but he fled and went straight to the Hathaways house to deal with Hank. Noticing that the adults were accidentally imprisoned, the Green Ghoul only frees Hank in order to deal with him personally. As Max and Taylor entered the room, Max was offered the chance by the Green Ghoul on becoming a real supervillain by joining him. As it first appeared that Max was willing to accept the offer, he attempts to ice breath him a few times. After being kicked out of Phobe's body by Miles, Max and Phobe both combine their ice breath on him and successfully froze and imprisoned the Green Ghoul.
- Ghost Powers: Green Ghoul has all the same ghost powers as Louie, Miles, and Ray Preston, which are invsibility, intagibility, flight/levitation, teleportation, overshadowing/possession (the power to possess people), and telekinesis.
- Possession: The Green Ghoul used his overshadowing power through out the crossover episode. When the Green Ghoul overshadows a person he can match his voice to sound like the person he is overshadowing.
- He is a parody of the Marvel villain, Green Goblin.
- The Green Ghoul is a level 13 ghost surpassing Ray Preston.