Atomic Flounder is a major recurring character from the world-famous Nickelodeon animated series, SpongeBob Squarepants. Back in the day, Atomic Flounder was one of the most heinous adversaries of Mermaid Man and Barnacle Boy, on par with Man Ray and The Dirty Bubble. He was a mutant flounder who would fight them and try to take over the world.

Currently, Atomic Flounder is retired, much like the two superheroes who used to face him and now lives as a kind and timid old man, who does no wrong and is actually friends with his former rivals. However, he is not entirely redeemed, as he can still snap back to his old self at any time, which he has done on occasion.

In his current state, he is voiced by Carlos Alazraqui. His younger self is voiced by Dee Bradley Baker who also voiced Klaus Heissler from American dad.


Atomic Flounder is the result of a nuclear test experiment, which went horribly wrong, which is what turned him into the mutated domination he is now. During his youth, Atomic Founder would tangle with Mermaid Man and Barnacle Boy and give the duo horrible doses of radiation. He became horrible enough of a villain to be accepted as a member of The Bad Guy Club For Villains, working alongside many other villainous greats, such as Man Ray, The Dirty Bubble, Jumbo Shrimp, and Sinister Slug.

Decades later, Atomic Flounder would eventually retire from being a supervillain and give up his evil ways to live his twilight years in peace, not unlike Mermaid Man and Barnacle Boy.

In "Mermaid Man and Barnacle Boy 2", Mermaid Man and Barnacle Boy were driving SpongeBob around in the invisible boatmobile, when they passed by Atomic Flounder. Atomic Flounder was simply waiting at the bus stop, not doing anything wrong. From afar, Mermaid Man pointed Atomic Flounder out to SpongeBob and told him stories about how he used to be one of their greatest foes and warned him that at any point, he could snap and become evil again. SpongeBob took this as a sign that he should attack him and jumped right out of the boatmobile to do just that.

SpongeBob beat up and assaulted the poor, defenseless old man without warning, leaving Atomic Flounder screaming for dear life. Mermaid Man and Barnacle Boy had to come in and stop him, telling SpongeBob that he is no longer a threat. After SpongeBob finally let up, Atomic Flounder yelled at Mermaid Man and Barnacle Boy, scolding them for allowing the little runt to attack him like that. He told them that if he wasn't retired he would use his radioactive belch on them to burn their flesh off. However, at the time he was saying this, he was so overcome by his rage, that he accidentally unleashed this exact power, incinerating Barnacle Boy's face to a crisp, before begrudgingly rummaging away in a huff.

In "The Bad Guy Club For Villains", Atomic Flounder met up with the rest of The Bad Guy Club For Villains and made some mischievous plans with them. The Bad Guy Club For Villains came up with a new sub-club called The BGATFBC. While they did this, Mermaid Man and Barnacle Boy spied on them and followed them to stop their evil plans, which would be taking place at Hotel Evil.

At Hotel Evil, The BGATFBC went to the room, where they were going to have their meeting, only to find Mermaid Man and Barnacle Boy there. Mermaid Man and Barnacle Boy attacked them. Atomic Flounder fought with Mermaid Man in hand-to-hand combat.

Sinister Slug barfed a slimeball at Mermaid Man and Mermaid Man jumped out of the way, dodging it. The slimeball hit Atomic Flounder, getting him stuck to the ground. This led to Atomic Flounder becoming incapacitated and immobilized, making it impossible for him to fight.

Mermaid Man and Barnacle Boy finally rassled up The BGATFBC and pumped them for information on what they were all about. The BGATFBC revealed that their name stood for The Bad Guys All Together For Book Club and all they were doing was reading books. Atomic Flounder sarcastically asked them if they were going to imprison them for reading and Mermaid Man said that they would do no such thing and he let them go.

Powers & Abilities

  • Radioactive Belch - Atomic Flounder can burp out a geyser of nuclear chemicals, which have the power to burn someone's skin off. Even after retiring as a villain, Atomic Flounder has the tendency to use this power on accident, during instances of being severely angered.
  • Mutation - Atomic Flounder can mutate somebody else's body by touching them. He can grow extra limbs on someone else's body, which can develop minds of their own and be used to attack their root victim and even eventually, take over their entire bodies. However, these mutations can easily be undone, by coming in physical contact with Atomic Flounder again.




           SpongeBob Villains

Main Villains
Mr. Krabs | Plankton | Karen Plankton | Mrs. Puff

Major Villains
Flying Dutchman | Man Ray | Sinister Slug | Jumbo Shrimp | Atomic Flounder | Dirty Bubble | Bubble Bass | Plankton Family | DoodleBob

Movie Villains
The SpongeBob Squarepants Movie:
Mr. Krabs | Mrs. Puff | Plankton | Dennis | Karen Plankton | Victor | Cyclops | Boat Jacker | The Thug Tug Gang
The SpongeBob Movie: Sponge Out of Water:
Plankton | Mr. Krabs | Karen Plankton | Burger-Beard
The SpongeBob Movie: Sponge On the Run:
Plankton | Mr. Krabs | Karen Plankton | King Poseidon

Other Villains
Every Villain Is Lemons | Abrasive SpongeBob | Alaskan Bull Worm | Puffy Fluffy | Sergeant Sam Roderick | Tattletale Strangler | Lord Poltergeist | Carl | Big One | BlackJack SquarePants | Evil Alien Jellion Overlord | Sea Bear | The Moth | Hash-Slinging Slasher | Con Man | Master Udon | Evil Syndicate | King Gorge | The Mawgu | Don Grouper | Animatronic Hieronymus Glove | Gordon | Coupe | Triton | The Fisherman | Madame Hagfish | Dead-Eye Plankton | Art Appraiser | Miss Gretel Puss | Planktonamor | Dreaded Patrick | Karen 2.0 | Captain Scarfish | Dragon Jellyfish | The Jellions | SpongeBot SteelPants | Robot Plankton | Robots | Globulous Maximus | Flats the Flounder | ToyBob | Cuddle E. Hugs | Gale Doppler | Mini Doodles | Plankrab | Doctor Negative | Jelliens | Seymour Scales | Catfishstress | Octopus King | Swamp Natives | Hoodoo Guru | Earworm | Krabby Patty Zombies

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