While not discussed in the original book, a bonus feature at the end of the Classic Goosebumps reprint says that King Jellyjam was accidentally created when a camper left a cup of gelatin in a cave contaminated with radiation and filled with snails.
King Jellyjam had the power to control minds. Additionally, he had a foul stench and would sweat black snails through his pores. He often let out humongous burps that shook the ground with its tremendous force. Since King Jellyjam's fingers were too fat and clumsy to pick up anything lying on the floor of his cavern, he was unable to clean himself. Instead, he hypnotized the counselors, including one named Buddy to bring forth the strongest, most physically fit of campers to do the dirty work for him by testing them out by winning six sports in a row that each of them competed in. Unfortunately for the campers who won the sports and earned the Camp Jellyjam coins they won for each sport, King Jellyjam seemed to get dirty, sweaty, and smelly just as quickly as anyone can clean him. Because of this, King Jellyjam had them scrub him and hose him day-in and day-out. And if anyone stopped cleaning him, even for a brief moment, King Jellyjam would gobble them up then and there; at least three kids sadly fell victim to that. A little girl named Alicia realized what was happening and tried to warn everyone else at the camp, but the counselors caught her and she was forced to wash the evil purple blob too.
This went on for quite a while. Then, one night, a girl named Wendy snuck in and found out what was really going on, unbeknownst to King Jellyjam. And the next morning, she returned with her brother, Elliot (whom she stopped winning a race) and yelled at the kids washing King Jellyjam to stop and lay flat on the floor. The kids did so, outraging King Jellyjam and he was about to eat Alicia but was unable to pick her up, because of his hands being too fat and clumsy to pick up her or any of the other kids off the floor. He then tried to wash himself, only to have the same result.
King Jellyjam took notice of Wendy and realized what had happened; he was about to grab Wendy, but ended up suffocating in his own foul smell before he could do any harm to her.
King Jellyjam is seen in a dungeon at The Evil Knight's castle and his sweating snails gross the protagonist out.
King Jellyjam is seen as an exhibit in the Wax Museum, along with a few other Goosebumps characters.
King Jellyjam is portrayed by the Comic Shop's owner, Milo as part of a test to see they can defeat him the same way the real King Jellyjam was. Milo, in King Jellyjam's form would eat the protagonist or the protagonist becomes King Jellyjam and becomes famous in a horror show.
King Jellyjam is a huge glob of purple slime, with enormous watery yellow eyes, a fat-lipped, two-tongued mouth and wore a gold crown on his head.
King Jellyjam was a terrible and disgusting slob of a monster. And even he couldn't stand his own foul smell, which is why he forced the strongest campers to wash him frequently. He had no tolerance for anyone trying to rest for even a second and wouldn't hesitate to devour the poor kid if they did so, his way of forcing everyone else to keep working. In spite of how scary he was, King Jellyjam was a very weak monster, due to being unable to move properly in his huge size, his foul stench and his fat clumsy fingers, which have been his biggest weaknesses.
List of appearances
|The Horror at Camp Jellyjam||Main antagonist||July 1995||Goosebumps|
|The Knight in Screaming Armor||Cameo||September 1996||Give Yourself Goosebumps|
|Welcome to the Wicked Wax Museum||Cameo||December 1996||Give Yourself Goosebumps|
|Little Comic Shop of Horrors||Portrayed||May 1997||Give Yourself Goosebumps|
|Scary Summer - The Horror at Camp Jellyjam||Main antagonist||July 2007||Goosebumps Graphix|
- King Jellyjam bears some resemblance to the Star Wars character Jabba the Hutt as both are greedy, cruel, huge, and slug-like creatures.
- Later in a Q&A, R. L. Stine would confirm that King Jellyjam was inspired by Jabba the Hutt.
- In Goosebumps: The Game, there's a strange Jelly substance in the mall's candy store. It's unknown what it is, but it could be possible that it's King Jellyjam, or pieces of him.
- In a 2016 Reddit AMA, R.L. Stine claimed that King Jellyjam was the grossest character he's ever written.
- In the Goosebumps: Collectibles line, there is an action figure labeled "King Jellyjam", but the figure is based on Buddy, the counselor on the cover of the book.