Plankton

Sheldon J. Plankton is Mr. Krabs' nemesis and the main antagonist in the SpongeBob SquarePants television series as well as The SpongeBob SquarePants Movie, "The Great Patty Caper," "SpongeBob's Last Stand," "Truth or Square," "Atlantis SquarePantis," and "Frozen Face Off." He is also the largest protagonist villain, though in some episodes that mainly focus on him where he was not portrayed as an antagonist/villain. He operates a struggling restaurant called the Chum Bucket, located directly across the street from the Krusty Krab. His primary goal in is to steal the Krabby Patty secret formula and put Mr. Krabs out of business. Plankton succeeds at stealing the recipe in the movie, but his goal of world domination is thwarted by SpongeBob. In "Friend or Foe," it was revealed that Mr. Krabs and Plankton were once were best friends, but a dispute over the Krabby Patty recipe ended their friendship. Plankton, as his name suggests, is a tiny green plankton that can fit in the palm of one's hand. He has stubby appendages, and one yellow eye with a red pupil. He has long, skinny antennae with small black spikes sticking out along them.