Sheldon J. Plankton, most commonly known as Plankton, is one of the main characters of the Spongebob Squarepants (Series) series. He is a planktonic copepod who runs the Chum Bucket restaurant.
He is the main antagonist of the franchise. Plankton despises his rival, Mr. Krabs, for running a successful restaurant because his own business rarely gets any customers. His main goal is to steal Krabs' secret formula for Krabby Patties and to run Mr. Krabs out of business.