SpongeBob SquarePants and Patrick Star

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 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 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 title character SpongeBob became a merchandising icon during the height of the show's second season and has seen continued commercial popularity.

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.