Even with the outstanding Bikini Bottom Police Department on patrol and enforcing very strict laws, the criminal underworld of Bikini Bottom isn't stopping. From bank robbers to serial killers, the city's top criminals aren't holding back.
- The Street Racers - A group with the leader being a cool guy who loves to get into illegal street races. His accomplices are a young lady and a laughing muscle fish. His only appearance was in the episode "The Hot Shot," when the group in their race car raced SpongeBob and Tony Fast Jr.
- Tattletale Strangler - A serial killer who enjoys getting revenge by strangling people, and tried to strangle SpongeBob. His only appearance so far has been in the episode "SpongeBob Meets the Strangler."
- BlackJack - A bully at his young age who has been to jail for littering. He is SpongeBob's cousin as well. He was very big in his childhood, but now, he is very small. His only appearance so far was in the episode "BlackJack."
- Sheldon J. Plankton - A criminal who was wanted for multiple charges. He is the main villain of the show, always trying to steal the Krabby Patty secret formula from Mr. Krabs for his business.
- The Dirty Bubble - The nemesis of Mermaid Man and Barnacle Boy.
- The Atomic Flounder - Like Mermaid Man and Barnacle Boy, The Atomic Flounder is retired. He attended book club with other evil villains when he was young.
- Stickyfins Whiting - A notorious criminal who loves to steal jewelry and electronics. He only appears in "The Getaway."
- Dorsal Dan - A getaway driver who is Stickyfin's partner-in-crime. He only appears in "The Getaway."
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