The characters in the American animated television series SpongeBob SquarePants were created by artist, animator, and former marine biologist Stephen Hillenburg. The series chronicles the adventures of the character SpongeBob SquarePants and his various friends in the fictional underwater city of Bikini Bottom. Most characters are anthropomorphic sea creatures based on real-life species. Many of the characters' designs originated in an educational comic book titled The Intertidal Zone, which Hillenburg created in the 1980s.

SpongeBob SquarePants features the voices of Tom Kenny, Bill Fagerbakke, Rodger Bumpass, Clancy Brown, Mr. Lawrence, Jill Talley, Carolyn Lawrence, Mary Jo Catlett and Lori Alan. Most of the secondary, one-off and background characters are voiced by Dee Bradley Baker, Sirena Irwin, Bob Joles, Mark Fite and Thomas F. Wilson. In addition to the series' regular cast, various celebrities from a wide range of professions have voiced guest characters and recurring roles.

The show's characters have received positive critical reception and attention from celebrities. They have made frequent appearances in media outside of the television show, including a theatrical film series, many video games, and two spin-off series. The characters have also been referenced and parodied throughout popular culture. The character SpongeBob became a merchandising icon during the height of the show's second season and has seen continued commercial popularity.

Creation and conception Stephen Hillenburg originally conceived early versions of the SpongeBob SquarePants characters in 1984, while he was teaching and studying marine biology at what is now the Orange County Marine Institute in Dana Point, California. During this period, Hillenburg became fascinated with animation, and wrote a comic book titled The Intertidal Zone starring various anthropomorphic forms of sea creatures, many of which would evolve into SpongeBob SquarePants characters, including "Bob the Sponge", who was the co-host of the comic and resembled an actual sea sponge as opposed to SpongeBob. In 1987, Hillenburg left the institute to pursue his dream of becoming an animator.

Patrick, Mr. Krabs, Pearl, and Squidward were the first other characters Hillenburg created for the show. Many of their characteristics were based on Hillenburg's experiences during his time at the Ocean Institute or inspired by the traits of their species. Patrick's personality embodies the nature of the starfish; according to Hillenburg, they look "dumb and slow" but are "very active and aggressive" in reality, like Patrick.Hillenburg, Stephen. (March 1, 2003). The SpongeBob SquarePants Movie (The Case of the Sponge "Bob") (DVD). Paramount Home Entertainment/Nickelodeon. Hillenburg drew inspiration from his former manager at a seafood restaurant while creating Mr. Krabs. According to him, this manager was redheaded, muscular, and a former army cook; these traits were all adapted into Krabs' character. His decision to design Pearl was influenced by his regular supervision of whale watches at the Ocean Institute, as well as by a cetacean skeleton at the institute. He drew Pearl with an oversized, almost geometric head as a reference to sperm whales having the largest brain size of any extant animal on Earth. He designed Squidward as an octopus because of the species' bulbous mantle; the octopus, he said, has "such a large bulbous head and Squidward thinks he's an intellectual, so of course he's gonna have [one]". Hillenburg drew Squidward with six tentacles because "it was really just simpler for animation to draw him with six legs instead of eight".

Several additions were made to the series' main cast before and after Hillenburg pitched the series to Nickelodeon; in his series bible, he added Sandy Cheeks, a squirrel clad in a diving suit, as a new friend of SpongeBob. Plankton and Karen were included in his bible but were not meant to make regular appearances; Plankton's voice actor Mr. Lawrence said that he "was only supposed to be in one or two episodes, but I was a writer on the show and I really liked this character". Following his first voice recording, Lawrence drafted some of his own ideas, hoping to "prove Plankton could survive as more than a one-note character". From then on, Plankton and Karen's roles in the series grew as Lawrence wrote ideas to give them more personality; notably, he decided to write Karen as Plankton's wife, rather than just his computer as was originally intended. They were both officially promoted to main cast members in the credits of the 2004 theatrical film, in which they play central roles.

Hillenburg added Mrs. Puff in response to a request by Nickelodeon that SpongeBob attend school. Initially, Nickelodeon executives felt that children would not relate to SpongeBob because he was an adult. They told Hillenburg to make SpongeBob more childlike by making him attend school, with a schoolteacher as his authority figure. Hillenburg compromised by creating Mrs. Puff as SpongeBob's boat-driving teacher. This satisfied Nickelodeon's request while allowing SpongeBob to remain an adult character. According to Nickelodeon's SpongeBob BingePants podcast, Mrs. Puff's addition "saved the show" and caused Nickelodeon to agree to produce the series.

Beginning with the eleventh season, the series' writers began an effort to give more storylines to the four main female characters (Karen, Sandy, Mrs. Puff, and Pearl). This led to the creation of the "Gal Pals," a friend group between the female characters, first introduced in the episode "Girls' Night Out." In an interview with People, Lori Alan explained, "Little by little, we've really been able to have more female plotlines." Jill Talley added, "It's nice too for all the little girls out there to see representation on the show."

Main characters

SpongeBob SquarePants

SpongeBob SquarePants (voiced by Tom Kenny) is an anthropomorphic and energetic yellow sea sponge who usually wears brown short pants, a white collared shirt, and a red tie. Like real sea sponges, he can filter-feed and reproduce by budding. He lives in a pineapple house and is employed as a fry cook at a fast food restaurant called the Krusty Krab. He diligently attends Mrs. Puff's Boating School but has never passed the test; throughout the series, he tries his hardest on the exams, but remains an unintentionally reckless boat driver and often causes accidents. He is relentlessly optimistic and enthusiastic toward his job and his friends. SpongeBob's hobbies include catching jellyfish, blowing bubbles, playing with his best friend Patrick, and unintentionally irritating his bad-tempered neighbor Squidward. He first appears in "Help Wanted".

Patrick Star

Patrick Star (voiced by Bill Fagerbakke) is a pink starfish who lives under a rock and wears green and purple flowered swim trunks. His most prominent character trait is his extremely low intelligence. He is best friends with SpongeBob and often unknowingly encourages activities that could get the two into lots of trouble. While typically unemployed throughout the series, Patrick holds various short-term jobs as the storyline of each episode requires, particularly with various stints at the Krusty Krab. He is generally slow and even-tempered, but can sometimes get very aggressive, much like real starfish, and occasionally performs feats of great strength.

Squidward Tentacles

Squidward Tentacles (voiced by Rodger Bumpass) is a turquoise bad-tempered Giant Pacific octopus with a large nose who works as a cashier at the Krusty Krab, but despises his job and desires a much better life. He is SpongeBob's next-door neighbor with a dry, sarcastic sense of humor. His house is between SpongeBob's and Patrick's houses. He believes himself to be a talented artist and musician, but nobody else recognizes his abilities. He plays the clarinet and often paints self-portraits in different styles, which he hangs up around his moai house. Squidward frequently voices his great frustration with SpongeBob, but he genuinely cares for him deep down and will occasionally stick up for him. This has been revealed in the form of sudden confessions when Squidward is in a dire situation or when SpongeBob is severely treated unfairly.

Mr. Krabs

Eugene Krabs (voiced by Clancy Brown) is a red crab who lives in an anchor-shaped house with his daughter Pearl, who is a whale. He dislikes spending money but will go to great lengths to make Pearl very happy. Mr. Krabs owns and operates the Krusty Krab restaurant where SpongeBob and Squidward work. He is self-content, cunning, and very obsessed with the value and essence of money. He tends to worry much more about his riches than about the needs of his employees. Having served in the navy, he speaks like a stereotypical pirate and loves sailing, whales and sea shanties.

Plankton and Karen

Sheldon Plankton (voiced by Mr. Lawrence) and Karen Plankton (voiced by Jill Talley) are the owners of the Chum Bucket, an unsuccessful restaurant located across the street from the Krusty Krab. Their business is a commercial failure because they sell mostly inedible foods made from chum. Plankton is a small dark green planktonic copepod and the self-proclaimed archenemy of Mr. Krabs. His ultimate goal is to steal Krabs' secret formula for Krabby Patties, run the Krusty Krab out of business, and take over the world, but he never permanently succeeds, usually due to either SpongeBob and/or Krabs' efforts, his own incompetence and immaturity, or his own small size (except, temporarily, in The SpongeBob SquarePants Movie). Plankton is a skilled inventor and possesses a Napoleon complex due to his short stature. Karen is Plankton's own invention, a waterproof supercomputer who is more competent than Plankton, being the brains behind most of his evil plans to steal Krabs' secret recipe. She is married to Plankton and usually takes residence in the Chum Bucket laboratory. Karen speaks with a pronounced Midwestern American accent.

Sandy Cheeks

Sandy Cheeks (voiced by Carolyn Lawrence) is a brown squirrel from Texas who lives in an air-filled glass dome and wears a diving suit to be able to breathe underwater. When aquatic creatures enter her home, they wear helmets of water to survive. Sandy speaks with a Southern drawl and often uses Texas slang. Her hobbies include extreme sports, science experiments, and karate. Sandy is also a member of the Gal Pals, a friend group with Karen, Mrs. Puff, and Pearl.

Mrs. Puff

Mrs. Puff (voiced by Mary Jo Catlett) is a paranoid pufferfish who is SpongeBob's teacher at boating school, an underwater driver's education facility where students drive boats like cars. She wears a sailor suit and her school is a lighthouse. SpongeBob is Mrs. Puff's most dedicated student and knows the answer to every question on her written and oral exams, but always panics and crashes when he actually tries to drive. She puffs up into a ball when she is scared or injured. As a running gag, she is frequently arrested by the police, usually due to her being responsible for SpongeBob when he unintentionally causes destruction around Bikini Bottom during his boating tests.

Pearl Krabs

Pearl Krabs (voiced by Lori Alan) is a teenage sperm whale and Mr. Krabs' daughter. She wants to fit in with her fish peers, but finds this impossible to do because of the large size inherent to her species. She will inherit the Krusty Krab from her father when she grows older, but is still in high school and does not yet have a job at the family business. Pearl's favorite activities are working at the Bikini Bottom Mall, using her father's credit card to buy anything that is in style, and listening to pop music.

Gary the Snail