Karen Plankton is one of the main antagonists of SpongeBob SquarePants who is occasionally portrayed as an anti-hero. Karen's system is built into most of Plankton's inventions. She has two main forms: a big monitor on the wall of the Chum Bucket and a portable wheeled computer. Along with her role as co-owner of the Chum Bucket, she works as the busser, chef and cashier. She rarely has to fulfill these jobs due to the restaurant's unpopularity.
She is voiced by Jill Talley.
Plankton and Karen dated while Plankton was still in school. It was the day of their third date when Mr. Krabs and Plankton became enemies. When he and Karen got married, Plankton had a head full of hair and a bushy mustache.
A photograph of them at their wedding can be seen in Komputer Overloard.
She appears in The SpongeBob SquarePants Movie as the secondary antagonist, successfully helping Plankton to conquer Bikini Bottom for a while by brainwashing the citizens who were eating in the Chum Bucket. In the final battle between Spongebob and Plankton, she was last seen laughing as she was surfing through the crowd. She presumably redeemed herself after Plankton was defeated, as she was not seen with him as Plankton was arrested and taken away by the police.
Karen does not have a heart, as stated in a conversation between her and SpongeBob in "Friend Or Foe." However, this does not prevent Karen from expressing emotions or feeling true love for Plankton. She does not often show it, but Karen cares for Plankton more than anything else; almost everything she does revolves around helping him in some way to do. According to Plankton, Karen likes to take long walks on the beach, and talk about their dreams of conquering all of Bikini Bottom.
- In Salsa Imbecilicus, she, along with Sandy, want the Bikini Bottomites to get normal in Bikini Bottom University for learning Bikini Bottomites to get normal again.
- In Frozen Face-Off, she, along with Spongebob, Patrick, Squidward, Mr. Krabs, Gary, and Sandy, try and stop Plankton from his evil plans and she also zaps Plankton for his betrayal against her after leaving her to be almost frozen for good..
- In Karen 2.0, she defeats Karen 2.