Sheldon Plankton

Sheldon Plankton (mostly called Plankton) is Mr. Krabs' rival and enemy and former best friend. He is one of the main characters on the show. He's always trying to steal the Krabby Patty Secret Formula.

Appearance
Plankton is a tiny zooplankton who is green, with large antennae.

Personality
Plankton is the main antagonist of the show. He sometimes is seen as the protagonist or anti-hero of the show. He is the owner of the failing Chum Bucket restaurant and is always trying to steal the Krabby Patty formula from Mr. Krabs to rule the fast food industry and the world (eventually). He is also seen to be a scientist, and is married to a computer that he built himself, Karen.