Nickelodeon's SpongeBob Squarepants is a long-running animated children's show known for its large cast of hilarious characters and its at times, dirty more adult jokes. SpongeBob, Patrick, and Squidward are the most recognizable characters of the series, but the show delves into other characters' lives in Bikini Bottom as well.
These side characters have only appeared in a handful of episodes and usually aren't the focal point. Despite that, some of them managed to leave a lasting impact. Fans remember them even years after their appearances because of how great they were.
Squilliam Fancyson
Squilliam Fancyson is Squidward's high school rival who is everything that Squidward wishes to be and Squidward will do anything to keep from him knowing his embarrassing job of working at the cash register of the Krusty Krab.
Squilliam is a snooty and wealthy character who also plays the clarinet to adoring fans. His most well-known episode sees him visiting the Krusty Krab, but Squidward and SpongeBob try to fool him into thinking it's an incredibly fancy restaurant.
Old Man Jenkins
Old Man Jenkins is a character that is always off to the side whenever he appears in SpongeBob and he usually only has small one-liners. They include him thinking a pole was a young lady, and he's hilariously appeared as several different fish throughout the series.
Old Man Jenkins is a running gag throughout most of the series and is a memorable character for his incredibly random appearances.
Mermaid Man And Barnacle Boy
Mermaid Man and Barnacle Boy show up frequently throughout SpongeBob and SpongeBob and Patrick are always delighted to see their two superhero idols.
They are semi-retired elderly superheroes who had a television show, just like Batman and Robin, when they were in their prime crime-fighting days. Mostly they talk with SpongeBob and Patrick in their retirement home and Mermaid Man loves screaming, "Evil!" That's enough to make them kind of iconic.
Flats The Flounder
Flats the Flounder is most-known for appearing in the episode "The Bully" where he continuously tells SpongeBob that he is going to "kick his butt" and bullies him throughout the entire day at Mrs. Puff's Boating School.
SpongeBob tries to get his friends to help him throughout the episode, but Patrick is friends with Flats and Mrs. Puff buys the lies that Flats tells her. Flats does get to kick SpongeBob's butt, but it doesn't affect SpongeBob at all due to his spongy body.
Bubble Bass
Bubble Bass is an incredibly rude and condescending customer who always bosses everyone around at the Krusty Krab. He gives SpongeBob a difficult order to perfect when he visits and Squidward shows his relatable side as he hates when the difficult customer shows up too.
He's an old rival of SpongeBob's and has come to the restaurant to frustrate both him and Squidward. SpongeBob carefully makes the burger, but Bass claims that he forgets the pickles and causes a scene. He's a memorable villain and side character throughout the series.
The Hash Slinging Slasher
Squidward makes up the ghost story of the Hash Slinging Slasher, who used to be a fry cook at the Krusty Krab, to scare SpongeBob during his graveyard shift. Squidward says that the lights will flicker, the phone will ring, and a midnight bus that killed him will drop off his ghost at the Krusty Krab to haunt whoever is there.
The ghost story seems to become true as an ominous figure steps off the bus and slowly approaches the Krusty Krab as both Squidward and SpongeBob think he's the terrifying ghost. In the hilarious end, the Hash Slinging Slasher was a nervous young fish who was trying to apply for a position at the Krusty Krab.
Kevin C. Cucumber
Kevin is introduced as the famous leader of the Jellyspotters, a prominent group of jellyfish hunters who SpongeBob and countless others are obsessed with. Kevin is a rude and conceded sea cucumber and one-off character on SpongeBob, who is mean to everyone in the group.
He chooses to allow SpongeBob to try out for the Jellyspotters only to make fun of him the entire time. Even though Kevin is clearly a villain, SpongeBob is oblivious to this and his optimistic naive nature shines through.
Tom The Chocolate Guy
SpongeBob and Patrick try their best to sell their neighbors and friends chocolate throughout an episode of the series titled "Chocolate with Nuts" and run into Tom the fish sporadically throughout the installment.
They knock on his door early on, asking if he wants to buy chocolate, and he only responds by screaming the word chocolate at them over and over again until the two run away. They assume that Tom is angry that they offered him chocolate, but hilariously figure out that Tom just got so excited at the prospect of eating the treat that he couldn't contain himself.
Fred The Fish
Fred the fish shows up frequently throughout the series and is better known as the fish who screams, "My leg!" almost every single time he has appeared in the show. Most of the time he's off-camera and when destruction happens in Bikini Bottom, Fred is there and somehow always hurts his leg.
There are other characters on the show who scream this line, but Fred is the most recognizable side character who says it.
DoodleBob
SpongeBob uses a magic pencil to crudely draw himself and the drawing is brought to life, becoming the villainous DoodleBob. SpongeBob and Patrick convince the new doodle to play a prank on Squidward, but they decide he should be erased when DoodbleBob starts attacking Squidward.
DoodleBob fights back, erasing part of SpongeBob's house, and causing havoc around Bikini Bottom.