List of SpongeBob SquarePants guest stars

In addition to the show's regular cast of voice actors, guest stars have been featured on SpongeBob SquarePants, an American animated television series created by marine biologist and animator Stephen Hillenburg for Nickelodeon. SpongeBob SquarePants chronicles the adventures and endeavors of the title character and his various friends in the fictional underwater city of Bikini Bottom. Many of the ideas for the show originated in an unpublished, educational comic book titled The Intertidal Zone, which Hillenburg created in the mid-1980s. He began developing SpongeBob SquarePants into a television series in 1996 upon the cancellation of Rocko's Modern Life, which Hillenburg directed.The pilot episode first aired on Nickelodeon in the United States on May 1, 1999. The show's ninth season premiered in 2012, and 218 episodes of SpongeBob SquarePants have aired. A feature-length film adaptation of the show, The SpongeBob SquarePants Movie, was released in 2004; in 2015, a sequel, The SpongeBob Movie: Sponge Out of Water, was released.

Guest voices have come from many ranges of professions, including actors, athletes, authors, musicians, and artists. The first credited guest stars were McHale's Navy actors Ernest Borgnine and Tim Conway, who appeared in "Mermaid Man and Barnacle Boy," the show's sixth episode. Borgnine and Conway have since been featured as recurring characters on the show. Rock band Ghastly Ones were the first guest stars to appear as themselves, appearing for a special musical performance in the first-season episode "Scaredy Pants." Aside from the aforementioned actors, actress Marion Ross has a recurring role as Grandma SquarePants, SpongeBob's grandmother. Borgnine has made the most appearances, guest starring 16 times. Conway has made 15 guest appearances, while Ross has appeared four times, John O'Hurley appeared three times, and John Rhys-Davies has appeared twice. Michael McKean also appeared twice, voicing different characters.

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