Plankton (SpongeBob SquarePants)

Sheldon James Plankton Jr., or more commonly Plankton, is a fictional character in the Nickelodeon animated television series SpongeBob SquarePants. He is voiced by Mr. Lawrence and first appeared in the episode "Plankton!" on July 31, 1999. Plankton was created and designed by Stephen Hillenburg. The character is also in video games and other merchandise based on the series. Mostly, he has been featured on countless toys, games, plushies, and other popular toys and games.

Role in SpongeBob SquarePants
Plankton is the arch-nemesis, but former best friend, of Mr. Krabs. He operates the Chum Bucket, located directly across the street from Krabs's restaurant, the Krusty Krab. The restaurant primarily sells chum, considered mostly inedible by the residents of Bikini Bottom, and as a result his restaurant is a total commercial failure. His primary goal in the series is put Krabs out of business (thus gaining a monopoly on the restaurant business) by stealing the "Krabby Patty formula," a secret recipe used to make the Krusty Krab's flagship sandwich; however, every attempt to do so has ultimately failed. The only time he has stolen it and made perfect Krabby Patties, was in the "The SpongeBob Squarepants Movie". He is often stepped on while trying to leave the Krusty Krab with the formula. It has been stated that Mr. Krabs and Plankton were once best friends, but a dispute over the Krabby Patty recipe ended their friendship.

A running gag throughout the series is the fact that Plankton is much smaller than the other main characters; he is easily stepped on and/or sent flying back to the Chum Bucket with a mere flick of the finger. His small size has led to him developing a Napoleon complex, which is occasionally manifested as a desire for global domination (the most prominent illustration of this is in The SpongeBob SquarePants Movie).

Plankton has a large extended family, containing more than 10,000 members of different forms of plankton, most of whom resemble hillbillies.

Karen
Plankton is married to a supercomputer named Karen (voiced by Jill Talley). She is his W.I.F.E. (both as an acronym for "Wired Integrated Female Electroencephalograph" and in the sense of a female spouse). She appears to have her own sentient mind and enjoys putting him down, though it's shown that they love each other. She sometimes gets fed up with his antics and forbids him from returning home. She tends to give Plankton most of his ideas to steal the Krabby Patty, but he usually takes them as his own ideas.

Merchandising
Plankton has been featured in various merchandises such as plush toys. In 2006, Ty Inc.'s Beanie Babies introduced a plush toy based on the character as part of the SpongeBob SquarePants series.