Flatts the Flounder
A bully at Mrs. Puff's Boating School who wants to kick SpongeBob's butt.
- Ascended Extra: He was a background character for a few early episodes before coming into the spotlight as the infamous bully he's known as now.
- Big Bad: He's the main villain in "The Bully"
- Blatant Lies: He employs obvious lies very often, especially when covering his own ass. The most notable one is when he convinces Mrs. Puff that where he's from, saying that you want to kick someone's butt means you want to befriend them.
- The Bully: He threatens to kick SpongeBob's butt the minute he lays eyes on him.
- Catchphrase: "I'm gonna kick your butt."
- Demoted to Extra: After his A Day in the Limelight episode, he returns to being a background character. Like fellow bully Bubble Bass, he was absent for several years before returning. Unlike Bubble Bass, however, he has yet to have a speaking role in the later seasons.
- Early-Bird Cameo: He appeared in "Sandy's Rocket" as one of the people that SpongeBob and Patrick kidnap.
- Jerkass: He has no reason to antagonize SpongeBob, but does so anyway.
- Pushover Parents: His father is terrified of him.
- Ungrateful Bastard: He still wants to beat SpongeBob up even after the latter performs CPR on him.
A bubble-guy created by SpongeBob to be his buddy.
- The Bus Came Back: He reappears in Bubble Buddy Returns, and then again in Bubbletown.
- Companion Cube: He was created when SpongeBob needed a new friend. Turns out, he is sentient.
- Late-Arrival Spoiler: His appearance in Bubble Buddy Returns would already spoil for new viewers that he is a living, talking bubble.
- Real After All: Revealed to actually be alive and not a figment of SpongeBob's imagination at the very end of his debut episode.
- The Voiceless: He is silent in his debut episode, until the very end.
Sandy's pet caterpillar, who turned into a butterfly.
- Artifact Title: Despite being a caterpillar, he's still called "Wormy". After he metamorphosized into a butterfly, that only made him less like a worm than before.
- The Dreaded: Inadvertently becomes this to SpongeBob, Patrick and the rest of Bikini Bottom when he transforms into a butterfly overnight, causing mass hysteria even though he's harmless.
Kevin C. Cucumber
- Butt-Monkey: Kevin ends up getting injured a few times in this episode. Considering how much of a jerkass he is, his butt monkey status is well deserved.
- For the Evulz: He picks on and belittles SpongeBob and then tries to drive him off a cliff for no apparent reason behind his own amusement. And later it's implied that he's done this to all of his "biggest fans".
- Hate Sink: One of the biggest deliberately unlikable characters in the series along with Bubble Bass and Squilliam. Coincidentally, all three characters were voiced by Dee Bradley Baker.
- I Want My Mommy!: Breaks down and cries for his mama after he and the other Jelly Spotters are trapped by the King Jellyfish.Help me, Mommy! Help me, Mommy! I want my blankie! I want my blankie!
- Jerkass: He acts smug and antagonistic towards SpongeBob, and his tests are just hopes of SpongeBob getting seriously hurt.
- Karmic Mutilation: He doesn't die, but he does get the fronds on his head torn off at the end of his episode. It should be Body Horror, but he deserved it for the massive jerk he was being.
- Kick the Dog: The way he taunts SpongeBob after he realizes that the Queen Jellyfish was fake was definitely the cruelest thing he did to him in the episode.
- Know-Nothing Know-It-All: The end of his first appearance reveals that he actually knows nothing about jellyfish, and the only reason he got into jellyfishing in the first place was because of the merchandise.
- Nice Hat: Subverted. It's actually part of his head.
- Noodle Incident: The King Jellyfish gets really angry when it sees him, implying that the two have some sort of history. It even bellows his name the minute it notices him.King Jellyfish: KEEEEEEVIINNNNN!!!
- Punny Name: His initial is C and his last name is Cucumber. He's a sea cucumber.
- Smug Snake: Constantly attempts to sabotage SpongeBob's attempts to get into the Jelly Spotters and is always convinced that his plans won't fail. Except they do fail. Constantly. And hilariously.
- Species Surname: He's a sea cucumber, and Cucumber happens to be his last name.
- Stealth Insult: The crown is the butt of the sea cucumber. Kevin literally has an asshat (or a butthead).
- Ungrateful Bastard: Even after SpongeBob saves his life, he's still a massive jerk to him!
An oyster at the Bikini Bottom Zoo.
- Punny Name: His name is a pun on Shamu.
SpongeBob and Patrick's creation, a crude doodle of SpongeBob come to life, and on an Unstoppable Rage.
- And I Must Scream: Inverted when SpongeBob trapped him in paper, making him Go Out with a Smile. However, this was how SpongeBob justified DoodleBob's Unstoppable Rage; He longed for a purpose.
- Ax-Crazy: He seems to love inflicting pain on others.
- Big Bad: He is the main villain in the SpongeBob edition of Drawn to Life.
- The Bus Came Back: He returns in "Doodle Dimension" after Patrick accidentally redraws him back to life.
- From a Single Cell: When SpongeBob destroys DoodleBob the first time, he forgets to erase Doodle's arm. Despite the rest of him being erased, the disembodied arm develops a mind of its own and re-draws DoodleBob exactly as he was before.
- Go Out with a Smile: When SpongeBob traps him in a book (presumably killing him off), his face goes from angry and confused to a genuinely happy smile.
- The Grotesque: Compared to SpongeBob, he's definitely uglier.
- Kill and Replace: "You Doodle, ME SPONGEBOB!!!"
- Mad Eye: Due to SpongeBobs poor drawing skill, one eye is a lot bigger than the other.
- Nightmare Face: He isn't very pleasant to look at.
- Super Strength: He can easily smash through rocks and throw people.
- Tragic Villain: How SpongeBob described him.Patrick: It's the evil doodle!SpongeBob: No, no, not evil. He was just a two dimensional creature, lost in our three dimensional aquatic world, longing for a purpose.
- The Unintelligible: His speech is mostly random gibberish.
- Vile Villain, Saccharine Show: Given that it's strongly implied he wanted to erase SpongeBob and take his place, he's definitely a rather dark villain for this kind of show, given that Plankton was a Harmless Villain and the Flying Dutchman wanted to be left alone.
Hash Slinging Slasher
- Accidentally Accurate: Zig-zagged. Squidward told the made-up story of The Hash Slinging Slasher, only for all of these details of the story to start happening in real life, and then we're given one final rug pull, when "The Hash-Slinging Slasher" emerges from the shadows and we find out he's just a harmless nerdy dork named Richard.
- Artificial Limbs: The Hash Slinging Slasher replaced his severed arm with a spatula.
- Butt-Monkey: The Hash Slinging Slasher accidentally chopped his own limb off, got hit by a bus, and at his funeral, he was fired from his job.
- Emerging from the Shadows: That's How The Hash-Slinging Slasher or "Richard" makes his debut.
- The Un-Reveal: Turns out that the horrifying silhouette of the Hash-Slinging Slasher was just a regular guy named "Richard" all along, just politely applying for a job.
Alaskan Bull Worm
- Ascended Extra: Has made a couple of cameos in other SpongeBob source material, its most prominent appearance being in SpongeBob SquarePants: Creature from the Krusty Krab as the game's resident Womb Level.
- The Dreaded: One of the few legitimate examples in the series, being a monster worm capable of devouring anything.
- Extreme Omnivore: The Alaskan Bull Worm has an appetite for just about anything it comes across. This is taken to its logical extreme in SpongeBob SquarePants: Creature from the Krusty Krab where its bowls are littered with inedible junk that can't be digested.
- Red Herring: When Sandy encounters what she believes is the Worm inside a "cave", she manages to give it a beating and tie it up, only for SpongeBob to tell her that what she just defeated isn't the Worm itself, but its tongue.
Mystery the Seahorse
The skeleton of dead fish, who was buried with a soda drinking hat.
- Decapitation Presentation: Inverted, when he carried his own dismembered head when rising from the grave.
- Everyone Has Standards: Smitty becomes disgusted when Mr. Krabs mentions that his undead army will eat out his innards and leave his corpse for the buzzards. He just simply wants to take his hat back from him.
- Nice Hat: His #1 soda drinking hat.
- Overly Long Name: Smitty WerbenJagerManJansen.
- Resurrection Revenge: Smitty rises from the dead to summon an army of skeleton zombies on Mr. Krabs for robbing his grave and stealing his hat.
- Rise from Your Grave: Smitty rises from his grave to get revenge on Mr. Krabs.
A famous octopus renowned for his soothing clarinet performances.
- Ascended Extra: He was originally a mysterious man who was seen playing for the creatures that look suspiciously like Squidward's "Smelly" form at the end of "The Thing". He later became Squidward's main objective in "Smooth Jazz at Bikini Bottom", where he wants to listen to and meet him at one of his concerts.
- Mellow Fellow: He's unlike most other cephalopods seen in the show in that he's a pretty chill guy who likes to play soothing clarinet pieces.
- No Celebrities Were Harmed: He's a parody of saxophonist Kenny G.
SpongeBob's badass, sociopathic cousin who would very often challenge him to fights before being arrested.
- Arson, Murder, and Jaywalking: As much as he tormented SpongeBob in their youth and is an all-around thug, he ultimately served ten years in jail after littering.
- Badass Baritone: Has a gruff voice delivered by John DiMaggio.
- Big Brother Bully: Or rather "Big Cousin Bully". He very often psychologically and physically tormented SpongeBob in his childhood years by exploiting his cowardliness.
- Disproportionate Retribution: He was sentenced to ten years in prison for...littering.
- Jaywalking Will Ruin Your Life: He serves a 10-year sentence all because he littered, which is nothing compared to the real line he crossed.
- Jerkass: He carelessly tormented SpongeBob in his childhood, and a decade after being paroled, he still hasn't learned his lesson. Fortunately, that doesn't mean he still poses a threat.
- Villain Decay: Despite him and SpongeBob now being in their adulthood, and acting as threatening as ever, he only grew up to be no bigger than SpongeBob's foot.
- Would Hurt a Child: He willingly assaulted SpongeBob in his childhood years.
A vicious nudibranch whom SpongeBob bought for Gary so he could have a playmate to keep him company while his owner is at work, and SpongeBob thinks Gary is ignoring him whenever he attacks him when not present.
- Bitch in Sheep's Clothing: At a first glance, he seems like an adorable, innocent little creature, but once exposed to sea snails, all hell will break loose.
- Ironic Name: He's anything but puffy or fluffy.
- Jerkass: He solely exists to endanger the lives of snails.
- More Teeth than the Osmond Family: His teeth are very jagged and nasty-looking, complete with prehensile tongues with extra teeth!
- One-Shot Character: Only appears in "A Pal for Gary".
- Vile Villain, Saccharine Show: Would anyone expect this sort of frightening abomination to show up on the show? He also tries to devour SpongeBob and Gary, wrecking their house in the process. Theres NOTHING funny about him, either.
Patrick's short-tempered, unpleasant, extremely stupid older sister.
- The Ditz: She's even more stupid than her brother, and that's saying something.
- Fat Bitch: She's a very overweight and hostile individual.
- Fat Idiot: Moreso than her brother.
- Hair-Trigger Temper: The episode even gives us this exchange:
- Hulk Speak: She speaks in this manner.
- Jerkass: She likes acting hostile and cold-hearted as well as destroying others' property out of pure anger.
- Knight Templar Big Sister: She's one to Patrick. For example, she attacks SpongeBob just for touching Patrick.
- Minor Insult Meltdown: When Squidward insults Sam, she starts huffing angrily, but then starts crying.
- One-Shot Character: Only appears in "Big Sister Sam".
- Series Continuity Error: In "Something Smells", Patrick said that he doesn't have a sister, which is contradicted by "Big Sister Sam" five seasons later... Though if "I'm With Stupid" is any indication, Patrick seems to have trouble with remembering his family.
- You No Take Candle: She speaks in this manner along with Hulk Speak.
SquidmundA character who only appeared in the comic "Squidmund Visits", Squidmund is Squidward's cousin.
A fish well known for saying "CHOCOLATE!"
- Ax-Crazy: Even before the "CHOCOLATE" incident, there were a few instances where he was pretty terrifying.
Tom: He burned our crops, poisoned our water supply, and delivered a plague unto our houses!!!Townspeople: He DID?!?Tom: No! But are we gonna wait around until he does?!?
- When SpongeBob says "April Fools" when he gives him back his drink, he grabs SpongeBob by the shirt and screams, demanding to know what he's done.
- When Bubble Buddy first was in Bikini Bottom and wreaked havoc, he piped up with this exchange.
- Comedic Sociopath: He qualifies to some extent, given how unpredictably hostile he can be.
- Early Installment Character-Design Difference: In his first appearance, he was red-skinned and much pudgier than he is now.
- Large Ham: A prime example is when he chases after SpongeBob and Patrick for selling him chocolate in "Chocolate with Nuts". 'CHOCOLATE! CHOCOLATE!'
- No Indoor Voice: He shouts a lot of his dialogue.
- New Job as the Plot Demands: He's been a bartender, a cameraman, a mattress salesman, a tour bus driver, an actor, a retirement home orderly, a business executive, a dentist, and a bank teller.
- One Steve Limit: Averted. If "Mermaid Man and Barnacle Boy V" is to be believed, Tom is also the name of a generic blue fish who gets harassed by E.V.I.L. at makeout reef.
- Only Sane Man: Tom is usually this due to his laid-back behavior.
- O.O.C. Is Serious Business: Although he's one of the sanest characters, he goes berserk when during his infamous screaming of chocolate.
- Palette Swap: Into red and lime green.
- Serious Business: Apparently food. It took three days to make the potato salad SpongeBob inadvertently ruined in "No Weenies Allowed", he screamed at SpongeBob for forgetting his drink in "Pizza Delivery", nearly assaulted him over ice cubes in "Fools in April", and of course his infamous screaming of "CHOCOLATE!" in "Chocolate with Nuts".
- Trademark Favorite Food: Do we even have to say what his favorite food is? 'CHOCOLATE! CHOCOLATE!'
A surfer fish who appears mostly in the background, but has some major roles.
- Dropped a Bridge on Him: Subverted. He appears to be killed off in a contrived manner when he drowns in "Bubble Buddy", but he comes back in later episodes alive and well. Unless he's a ghost and Nickelodeon's Bikini Bottom Mysteries episode on him can be taken with some degree of canon.
- Recurring Extra: Whenever there's an episode set at Goo Lagoon, he's usually there.
- Surfer Dude: He can usually been seen indulging in the sport at the beach.
- They Killed Kenny: He died several times but came back in later episodes thanks to Negative Continuity.
- In "Bubble Buddy", he apparently drowned when SpongeBob left him buried up to his neck on the beach. He appeared later in that episode as a angel.
- In "Something Smells", he gets killed by SpongeBob's bad breath.
- In "My Pretty Seahorse", after he thinks Mystery the seahorse is a ride and inserts a coin into her, she kicks him and he explodes where he lands.
A yellow fish who mostly appears as a background character. However, he did have a major role in the episode "Plankton's Regular".
- A Day in the Limelight: The episode "Plankton's Regular", was all about Nat becoming a regular customer at The Chum Bucket.
- Borrowed Catchphrase: In "Squid Baby", Nat steals Fred's "My Leg!" catchphrase, in a rather witty and subversive manner.Nat: [horrified] MY FACE! MY FACE! [flatly] Also my leg, [horrified] BUT MOSTLY MY FACE!!!
- Continuity Drift: Nat's name has changed from episode to episode, often being "Tucker" or "Peterson" (as his first name). However, the Bikini Bottom Mysteries episode, titled him "Nat Peterson", making this the closest we have to an official name.