Kaiju

King Jellyjam is the main antagonist of the Goosebumps book The Horror At Camp Jellyjam.

Role in the Story
He first appears as the benevolent-looking mascot of Camp Jellyjam, a sports camp with a fiercely competitive spirit. Campers are awarded gold tokens called King Coins for winning, and if a camper earns six of them, they can participate in a victory march called the Winner's Walk. However, none of them are seen again after that.

The winners are taken to an underground cavern where they are used as slave labor for the real King Jellyjam, an enormous, disgusting, and horrible-smelling blob monster who excretes snails. The campers are forced to wash King Jellyjam 24/7 without taking any breaks, or they will be eaten. King Jellyjam's burps cause frequent earthquakes and the camp counselors are hypnotized to continue running the camp as a front to acquire more slaves.

Eventually, the protagonist helps the slaves escape being eaten by lying down as the beast has terrible grip. King Jellyjam dies when his slaves stop washing him, suffocating from his own horrible smell.