| Name | Animal | Actor | Description | Episodes |
| Squidward's Family | ||||
| Mrs. Tentacles | Octopus | n/a | Squidward's mother, resides in an Easter Island head similar to Squidwards'; the only difference is her home has womanish curly hair. | Fools in April, Krusty Towers, Ghost Host |
| Mr. Tentacles | Octopus | n/a | Squidward's father. He has not appeared on screen, only mentioned when Squidward claimed that his father loved him very much. | Krab Borg |
| Squidward's House | House | n/a | Owned by Squidward, shown living or moving | The Secret Box, Good Neighbors, Funny Pants. |
| Mr. Krabs' Family | ||||
| Mama Krabs | Crab | Paul Tibbitt, Sirena Irwin | Mr. Krabs' mother and Pearl's grandmother, very strict and no-nonsense. Her phone number is 791347. | Sailor Mouth, Mid-Life Crustacean, Enemy In-Law |
| Mr. Krabs' Father | Crab | n/a | Appeared in an old picture in Mama Krabs' house, spoken of in other episode. | My Pretty Seahorse |
| Plankton's Family | ||||
| Mrs. Plankton | plankton | n/a | Plankton's mother. Plankton believes she would be proud of him if he took over the world and she liked him the best. | Nicktoons Unite! |
| Clem | plankton | n/a | Cousin of Sheldon J. Plankton, but not evil genius like him. Illiterate. Seem to like root beer. | |
| Zeke | plankton | n/a | Cousin of Sheldon J. Plankton, but not evil genius like him. Seem to like root beer. | |
| Rufus | plankton | n/a | Cousin of Sheldon J. Plankton, but not evil genius like him. Seem to like root beer. | |
| Jeke | plankton | n/a | Cousin of Sheldon J. Plankton, but not evil genius like him. Seem to like root beer. | |
| Billy Bob | plankton | n/a | Cousin of Sheldon J. Plankton, but not evil genius like him. Seem to like root beer. | |
| Billy Jim | plankton | n/a | Cousin of Sheldon J. Plankton, but not evil genius like him. Seem to like root beer. | |
| Billy Willy Banana Fana Fo Filly | plankton | n/a | Cousin of Sheldon J. Plankton, but not evil genius like him. Seem to like root beer. | |
| Toad | plankton | n/a | Cousin of Sheldon J. Plankton, but not evil genius like him. Seem to like root beer. | |
| Enis | plankton | n/a | Cousin of Sheldon J. Plankton, but not evil genius like him. Seem to like root beer. | |
| Fletcher McGee | plankton | n/a | Cousin of Sheldon J. Plankton, but not evil genius like him. Seem to like root beer. | |
| Rainchild | plankton | n/a | Cousin of Sheldon J. Plankton, but not evil genius like him. Seem to like root beer. | |
| Karen | W.I.F.E - a computer | n/a | Plankton's Computer Wife. | |
| Mrs. Puff's Family | ||||
| Mr. Puff | Pufferfish | n/a | SpongeBob's drivers ed teacher.
Mrs. Puff's deceased husband; he was turned into a lamp by a fisherman. |
Krusty Love |
| Sandy's Family | ||||
| Pa | Squirrel | n/a | Sandy's father. SpongeBob referred to him as "Pappy," but Sandy calls him "Pa". | Sandy, SpongeBob, and the Worm |
| Ma | Squirrel | n/a | Sandy's strict stepmother in jail. | Driven To Tears |
