SpongeBob SquarePants stars a cast of ten main characters. They were created by Stephen Hillenburg, who worked as a teacher of marine science before becoming an artist. He was inspired to design a group of aquatic characters while working at the Ocean Institute in the 1980s.
The title character is a sea sponge named SpongeBob. He has two neighbors: a pink starfish named Patrick and an arrogant octopus named Squidward. He works for a miserly crab named Mr. Krabs, who lives in an anchor with his whale daughter Pearl. SpongeBob attends a boat-driving school where he is taught by a pufferfish named Mrs. Puff. He often visits Sandy, a squirrel from the land who lives in an air-filled dome. The villains of the show are a copepod named Plankton and his waterproof computer, Karen, who want to run Mr. Krabs out of business. SpongeBob also has a pet snail, Gary, who meows like a cat. Each episode features SpongeBob and at least one of the other main characters.
SpongeBob and Pearl were the first two characters that Stephen created for the show. He created SpongeBob because he thought it was funny to use the sea sponge—a "weird" sea creature and one of his favorite animals—as the lead character. He was inspired to create Pearl while supervising whale watches at the Ocean Institute. Stephen was particularly interested in the sperm whale, which he chose for Pearl's species. Most of the other main characters were invented for his series bible, a book that he used to pitch the show to Nickelodeon.
A new addition to the main cast, Mrs. Puff, was made at the request of Nickelodeon in 1997. They told Stephen that they would not produce the cartoon unless SpongeBob was a kid who went to school, with his teacher as a main character. Stephen was ready to "walk out" on Nickelodeon; he insisted that SpongeBob should be a childlike adult so that he could be universally relatable. He eventually came up with a compromise that he loved: SpongeBob would go to a boat-driving school, run by a pufferfish named Mrs. Puff. This satisfied Nickelodeon's requests for a teacher while keeping SpongeBob as an adult.
When Stephen Hillenburg first created SpongeBob, he wanted to use the most obscure sea creature he could think of. In a July 1999 interview for Nickelodeon Magazine, he recalled asking himself "What would be the funniest, weirdest kind of animal to be the star?"
He thought about this and selected the sea sponge as "the most ridiculous" animal. Natural sea sponges have amorphous, blob-like shapes, but they can be cut and shaped into rectangles for cleaning products. Hillenburg's first sketches of the character had natural blob shapes, but as he gave the character a nerdy personality, he decided that a "squeaky-clean square" like a kitchen sponge fit the concept.
Hillenburg wanted to name the character "SpongeBoy," but this name was already trademarked as a mop product. He renamed the character SpongeBob, taking inspiration from a previous character he created, called Bob the Sponge. He felt that the word "sponge" had to be kept in the name to prevent confusion over his species.
Pearl and Mr. Krabs
Pearl was the second character that Stephen Hillenburg created for the series. He worked as a teacher at the Ocean Institute in California for many years. There, he was a tour guide for whale watches. He also tended to a whale skeleton exhibit that kids could look at. Hillenburg was particularly interested in the sperm whale, the world's largest toothed predator.
Hillenburg thought it would be funny if Pearl was a self-conscious teenager who happens to be a ginormous whale. At first, he wanted her personality to match the actual traits of a sperm whale. Sperm whales have the biggest brain out of any living animal on Earth, so he wanted Pearl to be a super-smart math student. The writing team felt that most viewers wouldn't understand the reference, so this was dropped from her final character.
Since Pearl is a teenager, Hillenburg had to give her a parent figure. He wanted each main character to be a different species, making the cast more diverse and interesting. Thus, he decided to make Pearl's dad a crab rather than another whale. He named the crab "Mr. Crabs." This was later changed to Krabs, as Hillenburg thought K's were funnier.
Hillenburg based Mr. Krabs on his former boss at a seafood restaurant. This boss was red-faced and had a strong Maine accent that sounded like a pirate. Hillenburg decided that Mr. Krabs would employ SpongeBob at his restaurant, the Krusty Krab, where he lived with Pearl. He eventually designed an anchor-shaped house for them to live in instead, keeping the restaurant separate from episodes about the Krabs family's home life.
Pearl's bio in the pitch bible
Mr. Krabs' original name
Squidward and Patrick
Hillenburg felt that the bulbous head of an octopus made it look snobbish and pompous. He made an arrogant octopus character as a foil to SpongeBob's cheerful nature. He named the character Squidward because it played off of the real name "Edward," but his species was always an octopus. Squidward was designed with a round head, unlike squids, which have triangular heads.
He decided that Squidward would live near SpongeBob and work with him as well, giving them plenty of time to interact, much to Squidward's annoyance. He started thinking of ideas for stories about SpongeBob and Squidward together. His initial idea for a pilot episode was about them on a road trip, where SpongeBob's enthusiasm would clash with Squidward's naysaying. On the way, he wanted them to meet an angry starfish bartender who was mad that he was pink.
Hillenburg kept developing this starfish character, and he ditched the idea that he would be a bartender. He reimagined the starfish as Patrick Star, a friend and neighbor of SpongeBob's who would be a constant source of unintentionally bad advice. Patrick became the comic relief of the show.
Sandy was created as a thrill-seeking "surfer squirrel" who would make sporadic appearances, adding bursts of action and adventure to the show's underwater setting. Her original design included a wetsuit and an air tank, but she was redrawn to look more like an astronaut.
Hillenburg stated in 2014 that he created Sandy as "a strong female character that could be a friend to SpongeBob but not a love interest." However, Tim Hill wanted to add a romantic aspect to the show when he helped Hillenburg with the series bible. He suggested that there be hints of romance between SpongeBob and Sandy. Hillenburg was okay with this at first, and Sandy's original bio described her as the "apple of SpongeBob's eye." Later on in the show's run, he changed his mind and insisted that SpongeBob and Sandy would just be friends, not a couple.
Stephen Hillenburg called Mrs. Puff the "most important" character to the show's history, saying that she "saved" the show from not being greenlit. He created her as a new main character in 1997, shortly after he pitched SpongeBob to Nickelodeon. The network gave him a strict order: they would only produce the show if SpongeBob was a kid who went to school. Hillenburg was ready to "walk out" on Nickelodeon, because writing SpongeBob as a school-age child went against his creative vision.
However, he came up with Mrs. Puff and her Boating School as a compromise, allowing SpongeBob to attend school as an adult. Because Hillenburg began his career as a marine science teacher, Mrs. Puff was a personal character to him, and he channeled many of his experiences as a teacher into her character. He chose the pufferfish for her species to evoke the look of a car's airbag popping out.
Gary was not originally a main character. Stephen Hillenburg created Gary as a minor background joke; he thought it would be funny if SpongeBob's "pets" were a singing clam named Shelley and a meowing snail named Gary. He included these ideas in his series bible, not as major characters, but as "things in SpongeBob's house." As the first season went into production, the writing team found much more use for Gary than they did for Shelley. Nickelodeon's marketing team also found that Gary "emerged as an unsung hero" in terms of popularity with kids.
For season 2, Gary was promoted to the show's main character sheet. He was officially added on March 22, 2000. He was the first new main character to be promoted, but he would not be the last; Plankton and Karen were added later.
Plankton and Karen
Stephen Hillenburg included Plankton in his series bible in 1996. He wanted to use the character as a funny villain. However, he later feared that Plankton's stories would get repetitive and predictable. During the production of season one, Hillenburg demoted Plankton from a main character to a minor one; he insisted that Plankton would work better as a one-time guest star. However, Doug Lawrence loved the character. He used his writing and acting skills to prove that Plankton could work as a major antagonist. If Lawrence did not have a dual role as both the voice and writer for Plankton, his character would never have become a major villain.
Lawrence summarized Plankton's origins in 2015, saying 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 as Plankton, Lawrence wrote some of his own ideas for the character and passed them to Hillenburg. From then on, Plankton began to appear more often. Lawrence's most notable contribution was giving a personality to Plankton's "waterproof computer," named Karen after Stephen Hillenburg's wife.
He decided that Plankton and Karen should be an inseparable duo, with Karen as the brains of the operation, always supplying Plankton with evil plans. Lawrence said: "I want more Karen on the show ... The married life of an evil genius is the funniest thing to me, so in that regard [Karen] definitely enhances Plankton’s stories making him more than just your typical bad guy."
Lawrence says that Plankton and Karen finally became main characters after the third season. The credits of the 2004 movie were the first time that the SpongeBob franchise ever billed a "Main Cast" in its credits. Both Plankton and Karen, voiced by Lawrence and Jill Talley, were officially promoted to main characters in the film's credits. Since then, their stories have been one of the show's most popular and important elements.
The show's artists use a book called the Main Model Pack to keep the designs, colors, and sizes of the main characters consistent. The pack includes basic models, turnarounds, color keys, and certain costumes. The most important part of the pack is the "Main Characters Model Sheet," a 2-page spread showing all of the main characters' normal looks.
During season 1, the sheet only featured eight character models, in order: Sandy in her bathing suit, Sandy in her diving suit, SpongeBob, Patrick, Squidward, Mr. Krabs, Mrs. Puff, and Pearl.
In season 2, Gary was added to the sheet, and after season 3, Plankton was added. Karen was added to the "BG Layout Stock Pack," which includes layouts for the main objects, props, and locations (the Krabby Patty and Krusty Krab are also included). Her wall form is always part of the background paintings and is labeled Background. Her mobile form is considered a prop rather than a character model, and it is labeled Prop.