Sheldon J. Plankton
A small plankton who is Mr. Krabs arch rival. He intends on getting the secret Krabby Patty formula and putting the Krusty Krab out of business.
Plankton is a plankton and runs a "competing" (though remarkably unpopular) restaurant called the Chum Bucket, which is located directly across the street from the Krusty Krab. Despite its proximity to the Krusty Krab, the Chum Bucket itself is rarely seen in the cartoon, except for those episodes in which Plankton also appears. Plankton lives at the Chum Bucket with Karen, his dear computer W.I.F.E. (Wired Integrated Female Electroencephalograph), who irritates him to no end. Plankton's first name, Sheldon, is constantly made fun of by his computer wife. He acts as Mr. Krab's arch enemy, and is SpongeBob SquarePants' occasional nemesis, though many times SpongeBob is naive of Plankton's evil powers. Plankton has tried to befriend Spongebob, and even Mr Krabs, but failed. The Chum Bucket was once the Chumporium to trick Mr Krabs. Plankton also gambled with Eugene, yet always lost for 16 years. When he won Spongebob in a bet, he revealed he had faked losing til Eugene made a mistake. Plankton is a science wiz, and even knows how to induce thermonuclear fusion. His primary catch phrase is "You can't do this to me, Krabs! I went to college!!!", which he usually says while flying back towards the Chum Bucket after one of his schemes to steal the Krabby Patty secret formula has been thwarted, though it has been used in other contexts. Plankton has also been known to slam into the Chum Bucket's exterior after his failed Krabby Patty theft attempts, after which he would reply, "Ouch."
In Krabs a la mode, he froze the Krusty Krab with Mr Krabs's "precious" thermostat. He appeared looking bigger with different facial expressions.
His desire is to infiltrate the Krusty Krab and put Mr. Krabs out of business. All of his nearly successful but ultimately foiled plans involve getting hold of the secret recipe for the copyrighted Krabby Patty, the main food item served at the Krusty Krab, in order to get customers. Plankton frequently plays on the naive, trusting nature of SpongeBob to try and get the recipe, along with engaging in various forms of trickery or theft to get either a Krabby Patty or the recipe. These forms have ranged from posing as a psychiatrist for SpongeBob to using a self-controlled robot version of Mr. Krabs. Plankton is almost always scheming away in his laboratory. In The Spongebob Squarepants Movie, Plankton used buckets to control the citizens of Bikini bottom, though lost to the combination of Goofy Goober-ness and rock n' roll.
Plankton's best friend from birth was his future rival Eugene Krabs. Both Krabs and Plankton were considered outcasts by other children, because Krabs was poor and Plankton was a nerd and small. When they discovered selling burgers would make them popular, they decide to sell patties. They set up their shop in their headquarter (the dump) to sell the patties. No one would come to the dump, so they gave one to Old Man Jenkins, who had helped the Krabs family. The bad patty knocked out Jenkins, causing him to be sent to the hospital to recover. Strangely, he has appeared in other episodes. There are three possibilities: It could be that there are two old fish with this name, this Old Man Jenkins is the father of the OMJ that normally appears in other episodes (Plankton and Mr. Krabs' childhood takes place in the 1940s) or that it is just a goof. Plankton accused Krabs of what happened and vice versa. Plankton was dared to improve upon the recipe, but only ended up with the shard of the recipe which read "and a pinch of chum". Plankton stormed out of restaurant, and went to create his own recipe using chum, memory, and science. At school, Plankton attempted to sell his chum burgers in a chum bucket and failed, whereas Krabs succeeded with his Krabby Patties, which he had created by accident when Plankton had slammed the door. Ingredients fell in the patty batter, thus creating the patty. Plankton later named his restaurant the Chum Bucket, after the secret ingredient of the original failed patty recipe
Eye Color: Red and Yellow
Birthday: November 30, 1942 (age 64)
Height: 3/4 Inch
Weight: .02 ounces