Sheldon James Plankton is the main antagonist of SpongeBob SquarePants. He and his computer-wife, Karen, operate a struggling restaurant called the Chum Bucket, located directly across the street from the Krusty Krab. His primary goal in the series is to steal the Krabby Patty recipe and put his nemesis Mr. Krabs out of business. Karen comes up with many plans to help Plankton steal the formula, but he always fails in some way or another. He actually 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 best friends, but a dispute over the Krabby Patty recipe ended their friendship.
Plankton has spent a long period of time trying to destroy the Krusty Krab. He started dating Karen when he was still in school and when she was only a security system. They founded their restaurant sometime after Plankton ended his friendship with Mr. Krabs. As revealed in "One Coarse Meal", Plankton is afraid of whales like Pearl, enough to go insane. The reason is because a pod of whales ate his ancestors, as plankton are part of the normal whale diet.
Early life and career
Plankton's best friend from birth was his future rival Eugene Krabs, as revealed in "Friend or Foe." Plankton and Krabs were considered outcasts by other kids because Krabs was poor and Plankton was a nerd. When they discovered that money could bring them out of their poverty, they decided to make money selling hamburger patties, and set up a mini-restaurant in the local dump. At first, their burgers weren't successful; the first of their patties was tried by Old Man Jenkins, who was knocked out by the contaminated burger. Plankton started complaining about how Jenkins had been old and not able to handle the patty. Offended by this, Krabs tried to take the recipe from Plankton to improve upon. Plankton wanted to do this himself, but he only ended up with the corner of the recipe, which read: "And a pinch of chum." Plankton stormed out of the restaurant, and went to create his own recipe, using only his memory, the corner of the recipe, and science. At school, Plankton tried to sell his chum burgers in a chum bucket and failed, when 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 unsuccessful patty recipe. Mr. Krabs named his restaurant the Krusty Krab. To this very day, Plankton has been single-mindedly obsessed with obtaining the Krabby Patty formula and running the Krusty Krab out of business, often going to incredible and often ridiculous lengths to do so; in "SpongeBob's Last Stand," for example, he builds a massive highway that goes straight through Jellyfish Fields and over the Krusty Krab, leading right to his restaurant simply to do so.
In "Dunces and Dragons," it was implied that the fight between Plankton and Krabs began centuries ago when Plankton's evil overlord ancestor Planktonamor was vanquished by a Krabby Patty. Since there's not any feud between Krabs and Plankton in their early childhood, it's possible that these families settled their differences until the childhoods of Krabs and Plankton.
In a comic story, Krabs and Plankton are shown to have been college roommates. Their rivalry is shown to have been caused by a series of events, including Plankton being stepped on by Mr. Krabs, which didn't annoy him at all, being closed inside Mr. Krabs' book, which aggravated him a little, and Mr. Krabs going out with his date and Plankton's date, which marked the official start to their rivalry. Since it was revealed in "Friend or Foe" that they were rivals earlier than college, this story is likely non-canon. Even in the present day of the series, Krabs and Plankton are occasionally shown to somewhat get along, such as in "New Leaf" and "Best Frenemies".
Plankton's restaurant, the Chum Bucket, has always been extremely unsuccessful, not only because of competition from the Krusty Krab and Plankton's rude and cruel treatment of the people in Bikini Bottom, but also due to the extremely poor quality of the food and Plankton's constant failure to clean the place up. As its name implies, the Chum Bucket serves chum-based foods, all of which taste terrible. In "Plankton's Regular", the Krusty Krab adds chum to its menu in an attempt to steal Plankton's single regular customer (who was in reality being paid by Karen to eat at the Chum Bucket and pretend to like the food there). The customer is disgusted by their chum, and says that it is the second foulest thing he has ever tasted (it can be inferred that Plankton's chum is the number one worst). This implies that chum is inherently disgusting, and cannot be made to taste good, although is shown to be false in the Season 7 episode "Greasy Buffoons." Plankton used excess grease from the Krusty Krab's grease trap that was dumped near the Chum Bucket to make his sales skyrocket, although it is unknown if this made the chum taste good, as Plankton could have been lying, and his customers could have been tasting only the grease, as the flavor could have covered up the chum's flavor.
It should be noted that in real life, chum is made of grounded up fish parts that are inedible to humans, such as heads and guts, and is used as bait for sharks and similar creatures. This would mean that Plankton is killing fish (or at least collecting dead fish) and serving their remains to other fish. This has only ever been touched upon in "The Krabby Kronicle," where SpongeBob prints a story claiming this. However, SpongeBob was being tricked by Mr. Krabs into printing absurd lies to appeal to customers, and this story was supposedly false. It also possible, that in the alternate reality the show takes place in, chum might be made of something completly different (although still likely disgusting), like in the episode Spongicus, Plankton named of many weird things that make up his chum, and fish parts was not on the list.
Plankton has no regular employees, and runs the Chum Bucket entirely by himself, although he spends most of his time in his laboratory, due to having no customers. Plankton actually runs the restaurant only when he has potential customers. Also, when he does have customers, he also uses artificialy intelligent machines to cover the other positions.
Although it has been stated on multiple occasions that Plankton has never had a single customer, he has on several occasions had brief success, particularly in more recent episodes, such as "Spongicus" and "Chum Caverns." A fan once wrote to Stephen Hillenberg, questioning that, due to Plankton being a genius in the fields of robotics, inventions, and technology (including many other fields), why Plankton doesn't sell computers and the like instead of fast food (which would actually probably bring him much better success)? Hillenberg answered this with that Plankton has never gone this route, simply due to him having never thought of it before, and also due to the fact that Plankton is slightly incompetent, and also that he has terrible communication skills, he would probably ignore the person's idea until the last minute.
Plankton is married to Karen, a waterproof supercomputer. Plankton built Karen himself out of a calculator and a mass of wires. She was originally a simple security system, as revealed in "Friend or Foe," but has become more advanced as Plankton upgrades her and his other inventions with new technology. Karen lives in the Chum Bucket laboratory and is the source of his evil plans to steal the Krabby Patty formula. In the twelfth season, the two have a son named Chip Plankton who works at the bank.
Being a microscopic organism, Plankton's biological family numbers in the thousands. In "Plankton's Army", he recruits his entire family to help him steal the formula, thinking them all to be criminal masterminds like himself. However, much to his surprise, his family consists entirely of uneducated, red-necked hillbillies. These Relatives include (but are not limited to): Clem Plankton, Zeke Plankton, Rufus Plankton, Jeke Plankton, Billy Bob Plankton, Billy Jim Plankton, Billy Billy Bo Willy Banana Fanna Fo Filly Plankton, Doug Plankton, Ennis Plankton, and Rainchild Plankton, the only ones named.
Plankton's ancestors include the evil wizard Planktonamor and his wife Karen the Crystal Ball, who lived during medieval times and appeared in "Dunces and Dragons". Another is Dead Eye Plankton, a wealthy citizen who attempted a hostile takeover of Bikini Gulch but was defeated by Sheriff SpongeBuck SquarePants. Dead Eye Plankton lived during the Wild-West era and appeared in "Pest of the West".
Plankton appears in virtually all SpongeBob-related video games, usually as a major antagonist.
- In SpongeBob SquarePants: Battle for Bikini Bottom, Plankton devises a plan to take over Bikini Bottom and obtain the Krabby Patty formula by creating a robot machine called the Duplicatotron 3000. However, the robots don't obey him and begin mindlessly rampaging across Bikini Bottom because he forgot to set the switch from "Do not Obey" to "Obey." Plankton convinces SpongeBob and friends to defeat the robots (as SpongeBob believed that the situation was his fault) so that he can have enough time to fix the main Duplicatotron 3000 so he can take over the city be controlling the robot army.
- In The SpongeBob SquarePants Movie game, Plankton is the main antagonist, as in the movie.
- In SpongeBob SquarePants: Lights, Camera, Pants!, Plankton appears as a playable character. In the game, he uses a robotic suit to act in the auditions (the parts that are played). Also, the "Captive" role, as well as the auditions for it, take place in the Chum Bucket
- In Nicktoons Unite!, Plankton is one of the four main villains of the game. He uses a crab mech to fight the heroes.
- In SpongeBob SquarePants: Creature from the Krusty Krab, Plankton is one of 3 playable characters, as well as the final boss of the game. He enlarges a Krabby Patty to massive size, only to have it come to life and begin chasing him. Eventually, Plankton enlarges himself to gigantic size, and begins rampaging across the city in pursuit of the giant patty. He's eventually defeated and reverted to his original size by Patrick, who was playing as his alter-ego Starfish Man.
- In SpongeBob SquarePants: SuperSponge, Plankton has a brief cameo, in which he yells at SpongeBob for stealing his time machine ("Blast you, SpongeBrat! You have found my secret time machine! Well, whatever you do, make sure you fill it up before you bring it back!").
- In SpongeBob SquarePants featuring Nicktoons: Globs of Doom, Plankton and four other villains team up with the heroes to defeat Globulous.
- In Nicktoons Racing, Plankton appears as an unlockable character.
- Karen: See the page Karen Plankton.
- Robo-Krabs: Robot version of Mr. Krabs, with Karen's system built inside. Seen in "Imitation Krabs", Operation Krabby Patty, "New Leaf", and "Spy Buddies".
- The switch-lives-just-to-know-what-it's-like-o-microfier: Seen in "The Algae's Always Greener".
- Hypno-Pod: Hypnotizes jellyfish to be slaves as seen in the online game Plankton's Pernicious Plot.
- Time Machine: Seen in SuperSponge.
- Mind Control Bucket Helmets: Control's the mind of fish and turns them into Plankton's slaves.Seen in The SpongeBob SquarePants Movie.
- High-Powered Mechanical Bio Arm: Opens anything - revealed but malfunctioned in the episode, "Best Frenemies."
- Enlargetron: Makes things bigger, seen in SpongeBob SquarePants: Creature from the Krusty Krab.
- New computer inventions, seen in "Komputer Overload".
- The Dispictulator: A freeze ray Plankton used in Creature from the Krusty Krab.
- Brain-Powered Sponge-Robot: A robot modeled after SpongeBob that runs on brains.
- ToyBob: A second SpongeBob look-alike robot, which is turned on by a wind-up key on its back. It was used to frame SpongeBob in "It's a SpongeBob Christmas!"
- Pat-Bot: Built with a paddle ball, pogo stick, razor blade, and metal claws.
- Duplicatotron 3000: A machine that creates seemingly endless amounts of robot soldiers. Seen in SpongeBob SquarePants: Battle for Bikini Bottom.
- A running gag is that in many episodes he appears in, including the movie, he gets stepped on.
- It was revealed in one episode that Plankton is not actually green, his outfit is. Karen removes the green and we see an underwear clad pink plankton embarrased of his nakedness. He also has a rack with identicle green suits.
- Plankton is left handed.
- Plankton appears in the "United Plankton Pictures" logo.
- Interestingly, although his name is "Plankton," he bears more resemblance to the real-life class of Organisms, Copepoda (Cyclops), which feed on phytoplankton. Do note that plankton are known to come from a different Kingdom than Copepods.
- Despite all of Plankton's schemes, he has only been arrested two times, in the movie and "Krabby Road". He escaped from the cops in "Goo Goo Gas".
- Plankton should be able to remember the Krabby Patty Secret Formula from his encounter in the movie, although Stephen Hillenburg said that chronologically, The SpongeBob SquarePants Movie is the last part of the series. And also, he could have been in jail for long enough to forget and want to get the formula again.
- Plankton is college educated, which has become a running gag throughout the series, as he would usually shout, "I went to college!" while pointing at his eye as a pun whenever Mr. Krabs foiled him.
- Plankton is afraid of whales in "One Coarse Meal," but not in "The Algae's Always Greener."
- Out of his whole family, he seems to be the smartest, as his family is shown to be quite clueless and unintelligent.
- His family is made up of hillbillies, or what they appear to be, and he appears to have forgotten their stereotype after all these years, as in their episode, he believes they are "criminal masterminds" and when he sees them, he is shocked and says "I've been away from home longer than I thought." It is possible that after this, he was disgusted by their stupidity, and possibly taught them to be smarter.
- He real name is mention on "Plankton's Army."
- According to "Truth or Square", Plankton has made 1003 failed attempts to steal the formula.
- At 2 inches tall, Plankton is actually gigantic for his kind. They, of course, did that to make viewers see him on the screen.
- Plankton actually should be half the size of Spongebob, as Spongebob is four inches tall.
- In "Plankton!," Plankton has a lab, which is just a real Labrador.
- In later episodes, when Spongebob holds Plankton in his hand, he's bigger or Spongebob's hand is smaller; compare "Plankton!" with "Single Cell Anniversary" or "The Main Drain".
- In "The Main Drain" Plankton is unusually bigger than he is in other episodes.
- He and Mr. Krabs is the only in their family to ever make friends with each other, their predecesors are enemies.
- In several relatively recent episodes, the inside of his mouth was purple. But that was corrected back to red in later episodes.