The King Jellyfish, also known by his Latin name, Cnidaria Rex, is a giant male jellyfish that is the ruler of all the jellyfish, along with his wife, the Queen Jellyfish. He may also be the father of the pink ones. He only appears in the episode "I'm Your Biggest Fanatic" and the video game Battle for Bikini Bottom.


King Jellyfish is a giant translucent purple jellyfish that normally wears a red cape with white at the end of it and a golden crown with green gems on it.

Abilities and talents

Like most jellyfish, his tentacles are electric. Unlike most other jellyfish, he can shoot electricity.

He is the only known jellyfish that can talk as shown when he said Kevin's name.

I'm Your Biggest Fanatic 103

He seems to have an experience, or at the very least, an interest in football since he rams a cave while wearing a football helmet and jersey.


He appears to be nice to anyone he meets unless they trick him.

He seems to have a fondness for pie as shown when he was delighted by SpongeBob making a pie out of bubbles.


He is the king of all of the Jellyfish.


He first appears in "I'm Your Biggest Fanatic." He appears after Kevin the Sea Cucumber tries to trick SpongeBob into falling into a hole with a Queen Jellyfish Ship. The King Jellyfish thinks that the ship is the real queen jellyfish and he chases it until he hits a billboard for Kevin's Ointment. It breaks and the King Jellyfish realizes that it is a fake. He then notices Kevin. The King Jellyfish chases the Jellyspotters and SpongeBob into a cave. The King Jellyfish notices that the group has gone into a cave. He puts on a football uniform and starts hitting the cave. Eventually, he stops and Kevin sends an anchovy, who, at first, says it is okay to leave, but then gets electrocuted and returns. After the Jellyspotters give up, SpongeBob walks out. The King Jellyfish gets ready to electrocute SpongeBob. SpongeBob takes out a bottle of bubble soap and blows a bubble that looks like a pie. The King Jellyfish takes the bubble pie and leaves.

He later appears in Battle for Bikini Bottom. In this game, Squidward gets electrocuted by some jellyfish and SpongeBob says that the only way to cure severe Jellyfish wounds is to get some King Jellyfish Jelly. Squidward says that SpongeBob should scale Spork Mountain and fight the King Jellyfish. SpongeBob then scales the mountain until he reaches the top, where he finds the King Jellyfish singing in a giant shower. The King Jellyfish is angry at SpongeBob for interrupting his shower. SpongeBob then fights the King Jellyfish. SpongeBob wins and the King Jellyfish gives SpongeBob a jar of his jelly and leaves.

Villainous role

In Battle for Bikini Bottom, he is the boss battle in Jellyfish Fields on the top of Spork Mountain. The player, as SpongeBob, must defeat him to get his jelly to heal Squidward's wounds, which he got from Jellyfish shocks.


  • Queen Jellyfish - She is his wife. She rules alongside him.
  • Dragon Jellyfish - He is a possible ancestor of the King Jellyfish. If he is an ancestor, this might explain where the King Jellyfish got his electricity powers.
  • Other Jellyfish - He may be the father of all of the smaller jellyfish.


Relationship with SpongeBob

Since he does not remember SpongeBob in "Battle for Bikini Bottom" and SpongeBob was a little less nervous with the king in "I'm Your Biggest Fanatic," it can be assumed that they met in "Battle for Bikini Bottom." In that game, SpongeBob disturbs the King Jellyfish's shower and he gets angry. He seems to have a little of this anger in "I'm Your Biggest Fanatic". SpongeBob gave him a pie and now they are on good terms.

Relationship with Kevin the Sea Cucumber

In "I'm Your Biggest Fanatic," it appears that King Jellyfish is familiar with Kevin as he recognizes him and got angry with him for something that he may have done to him and then chases him, SpongeBob, and the other Jellyspotters.


  • King Jellyfish's Latin name is Cnidaria Rex. Cnidaria is the phylum of mostly aquatic marine invertebrates that have cnidocyte, a specialized stinging cell found in creatures such as jellyfish and sea anemone. Rex is Latin for king.