Plankton and Karen

Sheldon J. Plankton and Karen Plankton are a pair of fictional characters and the main antagonists of SpongeBob SquarePants, the Nickelodeon animated television series. They are respectively voiced by Mr. Lawrence and Jill Talley. Their first appearance was in the episode "Plankton!" that premiered on July 31, 1999. They were created and designed by the marine biologist and animator Stephen Hillenburg, the creator of the series. Hillenburg named Karen after his wife, Karen Hillenburg (née Umland).

Plankton and Karen are the married owners of the unsuccessful Chum Bucket restaurant. Plankton is an intellectual planktonic copepod and Karen is a waterproof supercomputer. Plankton shares a rivalry with Mr. Krabs, who owns the far more profitable Krusty Krab restaurant and sells a fictional burger called the Krabby Patty. Plankton and Karen often devise schemes to steal the secret Krabby Patty recipe from the Krusty Krab, but their efforts are always thwarted by Krabs and his employees.

Critics have praised the characters’ voices and dialogue together. They began as minor characters, but Lawrence developed their personalities throughout the show's early seasons and they eventually became the franchise's main antagonists. The Planktons play central roles in The SpongeBob SquarePants Movie, which promoted them both to main cast members in its credits, and in the 2015 film. They have also been featured in a variety of spin-off media, including tie-in publications, playsets and other merchandise.