* SpongeBob SquarePants — A very friendly and funny sponge that loves jellyfishing. He works at the Krusty Krab as the fry-cook.
* Patrick Star — SpongeBob's best friend, a dimwitted, pink starfish.
* Sandy Cheeks — A clever Texas squirrel that has to wear an oxygen tank to breathe underwater. SpongeBob does not have a crush on her.
* Eugene H. Krabs — A crab that is in charge of the Krusty Krab restaurant, where SpongeBob works. He is addicted to money and is selfish and greedy.
* Pearl Krabs — Mr. Krabs's teenage daughter. She is a whale who acts like a stereotypical American teenage girl. Her father thinks he's spoiling her when quite frankly he is doing the opposite.
* Squidward Tentacles — SpongeBob's next door neighbor and co-worker at the Krusty Krab, where he is the cashier. He hates SpongeBob and Patrick, and openly displays his hatred towards them, not that they ever truly understood. He believes he is an amazing artist and clarinet player, but quite the opposite in reality.
* Gary the Snail — SpongeBob's pet, his only sound is a "meow", similar to a cat. In fact, he is considered to be a sea cat, like a worm is considered a sea dog.
* Sheldon J. Plankton - A small plankton who is Mr. Krabs arch rival. He intends on getting the secret Krabby Patty formula and putting the Krusty Krab out of business.
* Mrs. Puff — Widowed, husband captured and turned into a pufferfish lamp. SpongeBob's pufferfish boating teacher. Mrs. Puff is eager to get SpongeBob out of her class.
* Mermaid Man and Barnacle Boy — Old, retired and foolish superheroes who are adored by Spongebob, Patrick, And People From The "Mermaid Man & Barnacle Boy" Fan Club.
* Larry the Lobster — Buff, good-looking and well-fit lobster, usually found at Goo Lagoon, Bikini Bottom's local beach.
* Perch Perkins - The Bikini Bottom TV Reporter.
* Tom Kenny: SpongeBob SquarePants, Gary the Snail, Narrator, Patchy the Pirate, Mr. SquarePants, miscellaneous characters
* Bill Fagerbakke: Patrick Star
* Rodger Bumpass: Squidward Tentacles, Dr. Gill Gilliam
* Carolyn Lawrence: Sandy Cheeks
* Clancy Brown: Eugene Krabs
* Dee Bradley Baker: Squilliam Fancyson, miscellaneous characters
* Mr. Lawrence: Sheldon J. Plankton, Larry Lobster, miscellaneous characters
* Lori Alan: Pearl Krabs
* Mary Jo Catlett: Mrs. Poppy Puff
* Sirena Irwin: miscellaneous characters
* Lauren Tom: miscellaneous characters
* Stephen Hillenburg: Potty the Parrot
* Brian Doyle-Murray: The Flying Dutchman
* Jill Talley: Karen (Plankton's computer wife)
* Paul Tibbitt: Mama Krabs ("Sailor Mouth", "Mid-Life Crustacean") Potty the Parrot Friend or Foe?
* Thomas F. Wilson: miscellaneous characters
* Carlos Alazraqui: miscellaneous characters
* Clea Lewis: miscellaneous characters
* Sara Paxton: miscellaneous characters
* Ollie Young: miscellaneous characters
* Ernest Borgnine: Mermaid Man
* Tim Conway: Barnacle Boy
* Charles Nelson Reilly: Dirty Bubble ("Mermaid Man and Barnacle Boy II")
* John Rhys-Davies: Man Ray
* Jim Jarmusch: self ("Hooky")
* John Lurie: self ("Hooky")
* John O'Hurley: King Neptune ("Neptune's Spatula")
* Kevin Michael Richardson: King Neptune (voice in "Party Pooper Pants")
* Amy Poehler: Grandma
* Pat Morita: Master Udon ("Karate Island")
* Martin Olson: live-action sequence as Chief of the Superheroes ("Mermaid Man and Barnacle Boy V")
* Junior Brown: Sandy Cheeks ("Texas"; sang the last line: "I want to go home.") NOTE: Brown also sang the entire "SpongeBob SquarePants Theme Song" over the closing credits; however, because Nickelodeon usually runs advertising or promotional spot announcements during the closing credit sequences, the soundtrack is obliterated on both Nickelodeon and Nickelodeon 2 telecasts of this episode. Junior Brown's vocals may, however, be heard in their entirety on broadcasts of "Texas" that are telecast on the NickToons network, which runs the credits without the promotional vocals that it adds on its two flagship stations.
* David Glen Eisley: SpongeBob SquarePants when he was singing the song ("Band Geeks")
* Pantera: "Pre-Hibernation" plays in "Pre-Hibernation Week"
* Ween: "Loop de Loop" is on a record Gary the Snail plays for SpongeBob to teach him how to tie his shoes in "Your Shoe's Untied."
* Patton Oswalt: Jim the Original Frycook in The Original Fry Cook
* Marion Ross: Grandma in Grandma's Kisses
* Gene Shalit: Food Critic Gene Scallop in The Krusty Sponge
* Mark Hamill: The Moth in Night Light
* Nigel Planer and Rik Mayall, UK comic actors (best known for anarchic 1980s sitcom The Young Ones) guest-starred as "Dr. Marmalade" and "Lord Reginald" in the episode "Chimps Ahoy"
* David Bowie: Lord Royal Highness in the "Atlantis Squarepantis" episode
* Christopher Guest: guest-starred as SpongeBob's klutzy cousin, Stanley SquarePants in the episode "Stanley S. SquarePants"