Back in 1989, the year of the meteor shower, it was shown that a meteor hit the field where Jeremy Creek was tied up as a Scarecrow. A young Lex was also nearby as the blast caused him to lose his hair. It was later revealed that Jeremy fell into a coma after the impact and didn't wake up until present day when he learned that the kryptonite granted him with electrokinetic powers.
Clark Kent's vulnerability to green kryptonite was also introduced in this episode when he tried to approach Lana Lang while she was wearing the meteor rock necklace. As soon as he got within five feet of her, Clark fell down and became sick. Whitney Fordman later used the same necklace to disable Clark and tie him up as a Scarecrow, unaware of the fact the necklace was the actual reason for Clark's weakness.
Greg Arkin, a bug collector had his bugs imbued with kryptonite radiation. While driving them to safety his car crashed and released the bugs, causing them all to bite him (it was later revealed that his mutation wouldn't be possible unless a large number bit him at the same time). He was then granted with numerous bug-like abilities, namely the ability to create spider web and enchanted strength and agility.
The battle between Greg and Clark happened inside the Creekside Foundry, a place filled with meteor rocks which gave Clark a lot of trouble. However, he managed to find a cover made out of lead which was previously revealed to be capable of blocking the radiation.
Coach Walt Arnold was exposed to green kryptonite in a sauna which caused him to receive pyrokinetic powers. He later locked Clark in the very same sauna which left him paralyzed, seemingly now knowing that kryptonite is his weakness. Jonathan Kent managed to find Clark in time, allowing him to confront Arnold who eventually became so upset that he burned himself to death.
Tina Greer suffered from soft bone disease when she was young, but she made a miraculous recovery at the time of the meteor shower. It also allowed her to change her appearance into anyone of the similar height or weight. While confronting Clark at the cemetery, Tina had Lana's necklace inside a pocket on her jacket, so she easily managed to upperhand Clark. However, she was unaware of kryptonite being his weakness so Clark easily managed to knock her out soon after she took off the jacket.
Sean Kelvin fell into icy kryptonite-infested Crater Lake, and when he exited he suffered from permanent hypothermia. He was eventually thrown into a small pond by Clark and trapped when it was frozen solid with him still inside it.
Clark met Cassandra Carver, an elderly lady who was blinded in the meteor shower, but due to the kryptonite she gained the ability to see the future. A fellow senior citizen, Harry Volk, fell into a pond with kryptonite rocks with his electric wheel chair and emerges as his younger self. Volk then went on a killing spree, before he inadvertently suffocated himself in a grain silo. When Lex went to Cassandra to have his future told, the vision she saw startled her so much she died before telling Lex anything.
Jodi Melville goes on a diet that is based on vegetable shakes grown from kryptonite infested soil. The meteor infested shakes sped up her metabolism so much, she lost weight overnight, but she can't get enough to eat so she started sucking the fat out a deer, and then a fellow student. Clark arrived in time to prevent Pete Ross from being her next meal, but falls prey to the kryptonite in her greenhouse. He manages to get far enough away from it to save himself and protect her from an explosion and then taken to the hospital for treatment. Lex funds Steven Hamilton to start research on the link between kryptonite and human health.
Earl Jenkins was suffering from uncontrollable seizures that he gained shortly after an explosion in LuthorCorp's mysterious Level Three involving a green mist. It was later revealed that trace amounts of kryptonite have been found under his skin and the violent seizures were trying to shake them out of his system. Even the small trace amounts of kryptonite were enough to weaken Clark to the point that he couldn't come within about five feet of Earl without losing his abilities. Earl was taken for treatment but it is revealed in the Chloe Chronicles that he died six months later. This marks the first known case of kryptonite being used in experimentation.
As Clark pulled Eric Summers up from his fall off the Smallville Dam, a bolt of lightning struck them and transferred Clark's powers through the meteor rock in Eric's backpack to him. After estranging himself from his classmates and family, Eric went back to the dam to attempt suicide. Clark arrived to explain that Eric can adjust to his powers, but this only angered Eric and he attacked Clark with a live power line. At the same time, Clark attacked Eric with Lana's meteor rock necklace and Clark's powers were transferred back to him.
While warning workers about a gas pipe explosion, Lana got caught in the explosion herself. She was thrown to the ground, covered in dirt and meteor rocks. The explosion resulted in her becoming psychically linked to Gary Watts, a corrupt deputy who later kidnapped Chloe and attempted to kill Lana.
Trapped in a lead crypt beneath a motor home, Jonathan and Roger Nixon attempted to tunnel their way out, but the tunnel collapsed, causing soil that was full of meteor rocks to fall into the crypt. Clark eventually found them and rescued them, but he was weakened by the meteor rocks. Jonathan told Nixon to get Clark away from the rocks, but Nixon slipped a meteor rock into Clark's pocket and dragged him outside, wanting to kidnap him to write his story. Jonathan made his way out of the crypt and fought Nixon until Lex shot him in the back.
Dr. Steven Hamilton's prolonged meteor rock exposure cause him to get hand spasms. After stealing Clark's ship from Pete's shed, Dr. Hamilton kidnapped Pete to get him to reveal who the owner of the ship was. When Pete refused to say anything, Dr. Hamilton decided to inject Pete with liquid meteor rock to give him tremors even more severe than his own. As the needle came closer to Pete's neck, Clark super-sped through the wall and destroyed the syringe with his heat vision. However, Clark was overcome by the meteor rocks while untying Pete, forcing him to explain that he was "allergic" to them. Pete untied his feet and sent Hamilton crashing into another table where a container of liquid kryptonite fell and dripped onto his head. Hamilton shook with blurring speed and died shortly after.
Jonathan and Pete figured out that red kryptonite in the school's class rings was causing Clark's rebellious personality. They found Clark in a cornfield, pursuing Jessie Brooks. Pete opened a lead box containing meteor rocks while Jonathan smashed the ring with a sledgehammer.
In a flashback to 1989, a meteor shower hit Smallville, sending meteor rocks all over town. Meteors struck the Smallville sign and overturned the Kent Farm truck before Jonathan and Martha found Clark.
Clark x-rayed Whitney Fordman and saw that he had the same oddly-shaped, meteor-rock laced skeleton that he saw inside Tina Greer a year earlier. Tina-as-Whitney later asked Lana if he could have her necklace as something to remember her by. With her hands on a piece of meteor rock, Tina morphed into Jonathan and subdued Clark with the necklace. She tied Clark up in the storm cellar with the necklace around his neck while she morphed into a copy of him, wanting to take over his life. As Clark struggled to free himself, his ship emitted a bright light which neutralized the necklace.
When Lex sent an insurgence team to bug LuthorCorp, they broke into the vault, expecting to find money or valuables. Instead, all they found was a cart of kryptonite bars and the key to Clark's ship. Clark broke into the building to save his mother, but he was weakened by the cart of kryptonite bars. Martha pushed the cart back into the vault and closed the door, restoring Clark's powers.
Infected by a parasite from the Kawatche Caves, Pete resisted Clark's attempts to take him to a hospital and used green kryptonite to incapacitate Clark. Later outside the Talon, Pete knocked Clark out by punching him while holding a meteor rock in his hand.
Kryptonite dust spores in the storm cellar caused Martha to become severely ill. Later, when Clark visited the cellar, he was exposed to the spores, causing him to become sick as well. They were both cured when Clark ship emitted a blast of energy, neutralizing the kryptonite.
Clark followed Eric Marsh to a foundry where he found Eric's friends heating refined meteor rocks they stole from a LuthorCorp truck and pouring it out into glass vials, which they used with inhalers to achieve super strength. When Clark was caught snooping around, he was weakened by the kryptonite and was thrown into the blast furnace. Fortunately, the guys left the building with the kryptonite, and Clark survived the fiery furnace. After the stolen meteor rocks were recovered, Pete helped Clark bury them in the woods.
Former LuthorCorp employee Pete Dinsmore developed a technique using meteor rocks to speed up cell growth. When Clark and Lana went to investigate the secret cloning lab in Dinsmore's basement, Lana knocked over a jar of refined kryptonite after being startled by the sight of a clone.
Clark's ship changed shape as it announced that it has been programmed with the memories and will of Clark's Kryptonian father Jor-El. It told him to return at sunset to leave Smallville and fulfill his destiny. With Pete's help, Clark stole Lionel's kryptonite key which he used to destroy the ship. When he placed the key in the ship, it exploded along with the key and created a massive electromagnetic pulse, flipping the Kents' truck.
To identify the sample of blood Clark stole, Jonathan held a meteor rock near it, causing it to boil. Morgan Edge came by later demanding the blood which had already been destroyed. To prevent him and his thugs from killing his parents, Clark cut his wrist with kryptonite and bled into a jar, giving Morgan Edge a blood sample that matched the one he previously had. Edge realized that the source of the blood could be worth an endless amount of money, so he had his thugs kidnap Clark. They taped a piece of green kryptonite to his chest and threw him into a moving van. Clark was able to escape by cutting the duct tape with a shard of glass and using his heat vision to blow up the moving van.
Van McNulty was obsessed with getting rid of meteor freaks. After he killed one of them, he would leave a meteor rock with the word "freak" written on it next to their body. Van attempted to kill Lex, but Clark caught the bullet and attacked Van. A couple of meteor rocks rolled out of Van's backpack next to Clark, causing Van to realize that this was Clark's weakness. Later, Van went into the woods and made kryptonite bullets, using them to shoot Clark on the Kent Farm. Jonathan extracted the bullet from Clark and he regained consciousness later that day. Van shot Clark with kryptonite bullets again, this time in front of Lana, but Clark was wearing a lead plate under his shirt. Van was taken to Belle Reve.
While at the Lowell County fair, Lana and Chloe found snow globes filled with small meteor fragments which were being given away as prizes. Seth Nelson offered one of these globes to Lana even though she didn't win a game. An angry customer attacked Seth, smashing the kryptonite-filled snow globe over his head. Several meteor fragments got embedded in his head and mixed with his blood. During an MRI later, Seth's kryptonite-laced blood reacted badly with the MRI machine, shocking his body and giving him magnetic powers.
Morgan Edge was keeping a rosary of kryptonite beads in case he ever ran into Clark again. Clark tried to prevent Lex from shooting Edge, but he was incapacitated by the kryptonite beads, allowing Edge to beat him up. Lex shot Edge and almost shot Clark, but he realized Edge has disappeared. Clark was able to get away from the kryptonite beads in time to save Lex from being hit by Edge's car.
Ian Randall, Van McNulty, and Eric Summers decided to work together to break out of Belle Reve. Van paid an orderly to smuggle in a meteor rock. After Ian had his hands on it, he split into two and killed Van. When Clark came to break Lex out, Ian subdued Clark with the meteor rock and beat him up. The two Ians brought Clark to Eric, who used the meteor rock and an electric shock to leech his powers for a second time. Eric tossed Clark around and turned on Ian, but Clark found the meteor rock and took his powers back.
Walt Masterson and Nathan Dean robbed Smallville Jewelers while Clark was looking at a kryptonite necklace. While trying to shoot heat vision at Masterson, Clark's heat vision reflected back through the kryptonite necklace, temporarily blinding him.
Jonathan and Martha were each hypnotized by one of Molly Griggs' e-mails to kill Chloe. When Clark tried to help Chloe, Jonathan beat him up with a meteor rock. Chloe released several bales of hay from the upper floor of the barn, knocking Jonathan out. Both he and Martha snapped out of their trances.
Jordan Cross, a student who was born on the day of the meteor shower, has the ability to foresee death just by touching someone. When he touched Lana, he saw her as an old lady having a peaceful death. She was wearing the clear meteor rock necklace.
Jason Dante has been engineering cars that used a kryptonite boost to travel at extremely fast speeds. When Pete refused to throw a race for him, he attempted to kill Pete by placing a bomb in the engine of his car. Clark tried to call off the race, but Dante subdued him with a kryptonite booster and locked him in Pete's trunk. After Pete used the kryptonite boost during the race, Clark regained consciousness and punched a hole in the car's gas tank, preventing the bomb from going off.
Because Alicia Baker refused to tell the sheriff that she had harmed her father, Clark tried to trap her in a lead-painted room. He was unaware that Alicia overheard a conversation he had with his parents earlier about his meteor-rock weakness. Alicia incapacitated Clark with a meteor rock before going off to kill Lana. Clark escaped the room by kicking a can of lead paint onto the meteor rock, diminishing its effect.
Garrett Davis strapped a kryptonite bomb to his chest and threatened to detonate it if his brother, Vince Davis, didn't get a liver transplant. Sheriff Nancy Adams ordered a sharp-shooter to take Garrett out, but when he was shot, he accidentally detonated the bomb. Clark super-sped to the radiology department and grabbed a lead apron which he used to shield himself from the bomb's kryptonite radiation. He ripped the bomb from Garrett's chest and took it away from the hospital where it exploded harmlessly.
When Clark received Lana's frantic phone call for a second time, a bolt of lightning struck the telephone pole outside the youth center, causing the power to go off. The telephone pole landed in a puddle of water filled with kryptonite rocks. Clark used his x-ray vision to look through the wall and see the telephone pole on the ground with the electricity shooting through the puddle and into the wires. Outside, he lifted the telephone pole up to regain his connection to Lana while still keeping a safe distance from the kryptonite.
Using an employee's ID badge, Chloe sneaked into a secure LuthorCorp laboratory. Startled by the sight of a large dog, Chloe accidentally hit a button releasing a kryptonite gas, Levitas. With the gas now in her system, Chloe could force anyone to tell the truth, however, the gas had fatal consequences. Clark went to Jonah Doyle and got the antidote which he injected into Chloe.
Lex voluntarily underwent an experimental treatment in a kryptonite-filled memory tank at the Summerholt Institute. When he refused to end this treatment, Lionel sent Clark to Dr. Garner in exchange for ending Lex's treatments. As soon as Clark entered the memory lab, he was immediately overcome by the kryptonite, allowing Dr. Garner to knock him out and lower him into the tank. Clark went into severe seizures which destroyed most of the lab equipment. Lex entered the lab and smashed open the memory tank, saving Clark from drowning in kryptonite.
Thinking that Jeremiah Holdsclaw had his weakness as well as his abilities, Clark tried to subdue him with a meteor rock. Although the rock glowed green on his face, it appeared to have no effect on him. Jeremiah threw the rock across the loft before stabbing Clark with the Starblade.
In a flashback to Clark's freshman year, he attempted to dunk Lana in the school dunk tank, but his hands started shaking from the meteor rock in Lana's necklace. Back in his senior year, Dr. Elaine Fine developed a kryptonite-enhanced plastic surgery procedure which caused anyone who kissed the recipient to suffer from life-threatening hallucinations. The first recipient of this treatment was her daughter, Abigail Fine. Later, Dr. Fine caught Lois Lane investigating her, so she prepared to give Lois the treatment. Clark busted into the room and pulled the equipment away from Lois, however, kryptonite gas started filling the room. Lois fought off Dr. Fine and helped Clark from the room.
The cheerleaders of Smallville High spiked the football team's drinks with a kryptonite-enhanced love molecule to make their boyfriends devoted to them. People influenced by the love potion included Danny Cormay, Chloe Sullivan, Jason Teague, Clark Kent, and the rest of the football team. Although Clark did not become lovesick, he was considerably weakened until the kryptonite dripped out of his nose later that night. Everyone else was cured from the love potion after being exposed to intense heat.
Bart Allen opened a lead box containing a meteor rock in Clark's loft. Visibly incapacitated, Clark told Bart that he was allergic to meteor rocks. Later, Clark saved Bart and Lex from Hanison and his bodyguard, Tony, but Bart turned on Clark by weakening him with a meteor rock. Clark convinced Bart to do the right thing, and Bart closed the lead box before super-speeding away.
Lionel Luthor, transferred into Clark's body, almost choked Lex to death after finding out that Lex emptied his bank account. Martha sneaked up behind him holding a piece of kryptonite, but he was able to super-speed away. He then went to the Kent's house and demanded that Jonathan tell him what his weakness was.
After Mikhail Mxyzptlk caused Clark to trip and seriously injure another football player, Clark attempted to find a way to play like everyone else. He took a small piece of kryptonite and held in in his hand while throwing a football in his loft. Martha entered behind him, realizing that he never missed before. She ordered Clark to find out what caused him to trip instead of taking kryptonite out on the football field.
A lethal toxin that caused people to hallucinate their worst fears was released into the atmosphere. When Clark fell victim to the toxin, he hallucinated that another meteor shower hit Smallville. A meteor hit the hospital room where he was standing, weakening him in front of Lana. She realized that he came to Earth the day of the first meteor shower, and he was the reason that her parents are dead. Just as she was about to stab him with kryptonite, he woke up into reality.
Zach and Josh Greenfield have been using their two dogs, Einstein and Hercules, to commit robberies. Due to injections of kryptonite mixed with steroids, the dogs had super-strength. The brothers kept the dogs in cages with kryptonite vials on top to subdue their strength. When Clark set Einstein free, Einstein jumped out and smashed the kryptonite vials, weakening Clark. The brothers drove off with Clark and Hercules in the truck. Einstein, who had followed the truck, dragged Clark out just as the brothers were about to blow up the truck with Clark inside.
In the temple in China, Clark used his x-ray vision to find a secret chamber behind some Kryptonian symbols painted on the wall. As soon as he opened the chamber, he found an idol with kryptonite eyes and fell ill before the idol. A couple of guards helped him up and led him away from the chamber.
While super-heating green kryptonite, Lex accidentally created black kryptonite which split him apart from his evil alter-ego. Later, the good Lex showed Clark around a LuthorCorp lab where he revealed that he was trying to irradiate seeds to increase crop output. After being weakened by several large samples of kryptonite, Clark left the lab, unaware that he was being watched by Alexander. That night, Alexander met Clark in his loft, revealing that he knew about Clark's powers and his weakness. Clark grabbed Alexander's throat, but he was weakened by Alexander's kryptonite ring. Alexander left and Clark went to the Luthor Mansion to free Lex, but Alexander soon found them and overpowered Clark with the kryptonite ring again. He fought with Lex until Clark used his heat vision to turn the green kryptonite ring into black kryptonite, fusing the two Lexes back together.
Stuck-up prom queen candidate Dawn Stiles crashed her car into kryptonite-filled Carlton Gorge, giving her the ability to possess whoever she wants. During the night of the prom, she possessed Clark and attempted to burn down the school due to the fact that she was mad about not becoming the prom queen. Jonathan used a meteor rock to incapacitate Dawn-in-Clark and force Dawn's spirit out of Clark's body.
Kevin Grady, a person with the ability to erase people's memories, broke into the Summerholt Institute with Clark. They entered through the roof and found themselves in a room which contained a shelf with several jars of liquid kryptonite. Clark told Kevin to go on without him while he tried to escape the effects of the kryptonite. He released a rope tethered to the wall, causing a hook to come down from the ceiling and knock over the shelf containing the kryptonite. With his powers restored, Clark was able to rescue Chloe.
Smallville was hit by a second meteor shower, sending kryptonite all over the town. While retrieving the Stone of Water, Clark was rendered unconscious by several ancient idols embedded with green kryptonite in Lex's office vault. Chloe entered Lex's study and noticed Clark unconscious on the floor. She dragged him out and he super-sped away with the stone.
In a catatonic state, Lionel told Lana that meteor rock was the only way to defeat the Disciples of Zod. Lana arrived at the Smallville Medical Center and told the Disciples that Kal-El was hiding out at the Luthor Mansion. She directed them to the kryptonite-filled vault in Lex's study, but they realized it was a trap and closed the vault's door, sealing away the radiation.
A powerless Clark, glad to be free of his secret and his Kryptonian destiny, threw a meteor rock away in a field. Meanwhile, Tommy Lee and the twins escaped Belle Reve with the help of Lex. They had previously been given injections of a kryptonite serum at 33.1 to boost their powers. Eager for a fix, they forced Clark to break into LuthorCorp and retrieve the serum. With Chloe's help, Clark successfully broke into the vault containing the serum, but he was struck by the security lasers and got a cut on his arm. Unable to obtain the serum, Clark and Chloe came up with a different plan to overpower Lee and the twins.
Buffy Sanders was bitten in a cave containing meteor-infested stalactites that had mutated the bats living there. With Lana and Chloe now infected by the vampire rabies, Clark went to Lex, who showed him an injectable antidote that was kept alive by a large fragment of kryptonite. At this time, Lana arrived at the mansion and bit Clark, who was weakened by the kryptonite. He was able to grab a vial of serum which he later injected into Lana, restoring her to normal.
After a lecture from Milton Fine, Clark hallucinated that a meteor rock fell out of his backpack while a classroom projector displayed the words "I know how to kill you" on the wall. Soon after, a paranoid Clark attacked Jonathan, thinking he made a deal with Lionel Luthor. Chloe heard the commotion and subdued Clark with a meteor rock. Later, Clark hallucinated that Lex was going to kill him. Kryptonite gas filled the room, and Clark stumbled out.
In a quest to free General Zod, Milton Fine/Brainiac gave Martha a life-threatening bruise on her left shoulder. He advised the Kents to treat the bruise with a meteor rock, which would help ease the pain. Once Clark opened the portal for Zod in the Fortress of Solitude, Fine used kryptonite to incapacitate Clark, revealing he was actually created to free Zod. Meanwhile, Chloe found the key in the Kawatche Caves, teleported to the Fortress, and took the kryptonite off of Clark.
After the spirit of Gretchen Winters was released in the Talon, Clark used his x-ray vision and saw a skeleton behind a wall. He broke the wall open, exposing a body, but it was wearing a bracelet with a large kryptonite gem. Chloe touched the stone, and the girl's spirit transferred into her body. Later, Michael Westmore, Gretchen's killer, gave Gretchen/Chloe another kryptonite bracelet, revealing that his father used to make them. However, Gretchen touched Michael, and the kryptonite glowed, transferring Gretchen's spirit into Michael.
When Clark was under Simone's hypnotic control, Chloe took a chunk of green kryptonite from her desk at the Daily Planet to stop him. She met up with Clark at Lex's mansion and used the rock to weaken him until Simone's gem was shattered.
Lana met two med students, Lance and Ally, who developed a kryptonite-based serum that caused the user to die for a short moment of time, allowing the user to see their deceased loved ones. Lana, Lex, and Clark were all injected with the serum.
Graham Garrett used green kryptonite against Clark after he discovered his weakness while spying on him. Later, Chloe and Lois found an incapacitated Clark buried in the alleyway behind the Talon. Chloe threw the meteor rock away and Clark recovered
Duncan Allenmeyer was in a vegetative state because he was hit by a car several years ago. He was given an experimental medicine with meteor rock in it, allowing him to astral project out of his body and use psychokinesis.
While searching for Bart Allen in LuthorCorp's Ridge Facility, Clark accidentally entered a room used for refining meteor rocks. He was immediately incapacitated and unable to get up. Just as a security guard found him, Green Arrow shot the guard with an arrow and rescued Clark.
While under mind control by her mother, Chloe was instructed to get out of Smallville any way possible. She put a piece of kryptonite in Clark's jacket pocket so he could not prevent her from leaving. Martha arrived home and found Clark passed out on the floor. She put the rock back into the lead box and Clark awoke.
Lex was trapped in a series of underground tunnels, and Clark tried to help by going down there to get him. However, the tunnels were infested with meteor rocks, making it difficult for Clark to survive. Chloe also learned of the kryptonite when she saw one of the rescue workers with kryptonite dust on his vest. The worker explained that meteor rocks were in abundance in the tunnels.
Lionel brought green kryptonite in a lead box to Reeves Dam in case he needed to use it. He tried to use the kryptonite against Bizarro, but Bizarro absorbed the radiation, making him stronger and neutralizing the kryptonite.
Needing green kryptonite to power himself up, Bizarro went to the loft and used a meteor rock to heal a wound he received after Clark impaled him on an electrical pylon. Later, Bizarro asked Lex to help him kill Clark by giving him meteor rocks. Lex took Bizarro to a vault filled with kryptonite at Reeves Dam, where Bizarro absorbed the radiation, leaving the kryptonite clear, and harmless to Clark. Under the yellow sun, Bizarro was weakened enough that Clark was able to punch him away.
While heading to Reeves Dam, Clark and Lois discovered Kara Kent's spaceship, which was covered in algae and meteor rocks. Clark kept his distance from the ship while Lois went to investigate. Later, Kara said that she needed to find her ship, but the green rocks kept weakening her. Clark explained that the rocks were called kryptonite and could be potentially fatal.
Tyler Crenshaw, Tempest Grace, and Carly, also known as the Weather Girls, were caught in a storm during the last meteor shower, giving them weather-related powers. When Clark tried to stop Tyler and Tempest from taking a Kryptonian medallion, Tempest formed a tornado, blowing several meteor rocks onto Clark. Luckily, Kara arrived and used her heat vision to explode a meteor rock, restoring Clark's abilities. Carly died after Tyler froze her, and Tempest and Tyler are presumed captured.
Dr. Curtis Knox has been treating meteor-infected people and removing their abilities. One of his patients was Sasha Woodman, a metahuman who used to have the ability to control bees. After "curing" her, Dr. Knox abducted her, removing one of her organs. In the same room, several jars of refined kryptonite also contained organs from meteor-infected people. Dr. Knox was stealing organs from patients in an attempt to make his wife Sophia immortal. Chloe made an appointment to see Dr. Knox due to the fact that she wanted to get rid of her meteor infection. She was unaware that Dr. Knox wanted to steal her kryptonite-rich heart. Just as Dr. Knox started to press a knife into Chloe's chest, Clark super-sped in, but was weakened by the jars of kryptonite. While he and Dr. Knox fought, they destroyed the medical equipment, killing Sophia.
Agent Carter kidnapped Kara using green kryptonite handcuffs, claiming that he saw meteor rocks disable Kara's ship, so he figured it might do the same to the passenger. He took Kara to a kryptonite-filled lab in Virgina, where Kara was restrained on a table with a kryptonite IV in her arm, forcing her to relive prior memories. Clark broke into the lab to rescue Kara, but he was immediately overcome by the kryptonite, causing Carter to realize that he is also an alien. Although he was significantly weakened, Clark managed to attack Carter and remove Kara's kryptonite IV, but he saw Kara's flashback while disconnecting the rest of the equipment. At this time, Carter sneaked up on Clark with more kryptonite, but Lionel entered the lab and shot Carter. Kara, who had just died from kryptonite exposure, was saved after Clark resuscitated her.
When kryptonite mixed with a lightning strike, Lana received Clark's powers. Meanwhile, Lex and Dr. Jansen were observing Project Scion, a vial of alive liquid that was only subdued by meteor rock. Later, Lana attacked both Lex and Clark, causing Project Scion to fall out and weaken her and Clark. Clark smashed the vial, and used the kryptonite and an electric shock to take his powers away from Lana.
Clark discovered a crack in the floor of a gum factory filled with kryptonite. Unknowingly, Pete Ross chewed the kryptonite-laced gum and gained the power to stretch his body. Later, Pete detained Clark with a piece of green kryptonite from Lionel Luthor's vault to prevent Clark from stopping him from killing Lex. Pete's powers disappeared when he stopped chewing the gum.
Pierce and his team captured Clark by shooting him with kryptonite tasers. Pierce then kept Clark in a kryptonite-lined cell which allowed him to control the intensity of the kryptonite Clark was exposed to. After deciding that Clark was a dangerous threat, Pierce raised the kryptonite charge to its maximum, but Kara destroyed the cell and saved Clark. Pierce pointed a gun loaded with kryptonite darts at Clark and Kara, but Lionel killed Pierce.
Edward Teague used a piece of kryptonite to weakened Clark. Teague strapped the weakened Clark to an altar surrounded by liquid kryptonite and prepared an ancient Kryptonian ritual. Later Chloe got to the cathedral, and found Clark. She drained off the liquid kryptonite and freed Clark.
When Clark discovers that Kara is responsible for Edwards Teague's plane blowing up killing him and the crew on board. He confronts her suspecting that something happened to Kara when they returned from Krypton . Kara says she fine and she's just trying to protect the world by doing whatever is necessary to prevent Lex from controling him with the Veritas device. After a brief fight with Kara, Clark decide he'll use Kryptonite to get some answer from Kara. Chloe decide to use it instead since it won't hurt her. Chloe tricks Kara into coming to the talon and tries to use the kryptonite on her but discovers it has no effect on her . Kara makes a snarky remark : Check the expiration date? Chloe then learns a terrible truth that this is actually Brainiac in disguise as Kara Zor-EL .
Macy used a piece of kryptonite to weakened Clark after he tried to save Lois. Macy strapped the weakened Clark to an electrical chair. Though weakened, Clark headbutted macy away from him, causing macy to drop his kryptonite in Clark's hand and Clark through the kryptonite down a vent. Clark regained his powers and used his heat vision to create gas around Macy's lair. Clark used his super strength to knock out Macy and saved Lois.
When Doomsday attacked the barn where Chloe and Jimmy's weddings was being held, he attacked the people and threw Clark to the upper part of the barn where he barged into a set of draws and knocked out the green kryptonite. Lana came up to put it away as soon as she could be Doomsday already left with Chloe before Clark could recover.
Lex Luthor uses Winslow Schott to plant a Kryptonite Bomb on The rooftop of The Daily Planet as part of his ultimate Revenge plan against Clark & Lana. Lana has to make a choice between Clark and Metropolis. If Lana absorbs the kryptonite radiation into her power suit the city will be saved, but Clark can never come near Lana again. After one last kiss with Clark, Lana absorbs all of the kryptonite radiation.
When Clark attempts to use the Legion ring that's stored in the toolbox to change current events taken place. He finds instead Green Kryptonite in it's place by Linda Lake who's holding unto the legion ring and plaining on using it . If not for Lois Lane who defeats Linda and saves Clark by throwing the kryptonite away.
While at the Luthor mansion Davis Bloome remembers himself as a young boy playing with a young Lex Luthor. After winning the duel, Lex claims his prize a lead lined box supposedly made of St. George's Armor which contains a piece of green Kryptonite. When Lex opened the box Davis suddenly begins to scream in great agony. Not realizing what actually happened Lex closed the box and comforts Davis. Later, Davis asks Chloe for her help to kill him in a kryptonite cage to stop him from becoming Doomsday again.
The current Boss Of Intergang Ron Milano has discovered that he can make counterfeit money using kryptonite-laced ink. Later Clark arrives at the Ace of Clubs and uses his super-hearing to hear the flicking of the counterfeit money and Bruno Mannheim talking. He super-speeds into the room but the kryptonite-laced money weakens him instantly, Mannheim & his goons discovers Clark and begin interrogating him. Suddenly Lois as Stiletto arrives to save Clark and Jimmy . After making quick work of Mannheim and his goons. Lois goes to check up on Jimmy just as Bruno comes to and draws his gun, preparing to shoot her. Clark, weakened by the kryptonite-laced money, calls to Lois to warn her, and just as she turns around, the bullet is fired. Clark scrambles to jump mid-air and sail in front of the bullet, protecting Lois and getting shot in his side in the process.
After Rudy Jones absorbed Clark Kent powers . Oliver as Green Arrow wearing Lex's Kryptonite ring viciously beats Rudy up until Clark tells him to stop. Clark then grips Parasite, who gives Clark back his powers to stop the pain due to Kryptonite exposure. Oliver leaves with ring which Clark notices .
Black Canary & Impluse summon Clark to the location where Chloe and Davis are. Only he arrives to discover it's a trap set by Green Arrow who shoots him with a kryptonite dart. Clark collapses and tells them they're making a big mistake. Jimmy arrives on the scene looking for Chloe, and finds Clark with the dart in his back. Clark tells him to remove the dart, and Jimmy notices that the kryptonite glows the closer it is to Clark, who warns him away when he puts it close. The cut on Clark's face then heals and Jimmy notices it, realizing Clark is super human. Clark admits to being the Red-Blue Blur and compliments Jimmy on putting it all together as well as being right about Davis. Clark tells him that he needs his help and to get Chloe and Davis to his wedding present before super-speeding away, leaving Jimmy in awe.
While trying to rescue Lois, Clark is exposed to the Kryptonite tubes located in the Project Intercept device that allows him to see Lois' memories of her visit one year into the future. In that alternate future Clark sees Major Zod and his army as the rules of earth with himself powerless under a red sun. Chloe as the leader of the rebels with Oliver by her side using a bunch kryptonite laced weapons (Arrows & Swords) to defend themselves against the kryptonian armada. Oliver gives a kyptonite laced blade to Lois for her to use to defend herself, she attempts to pass it to Clark while he's battling Zod, however Zod retrieves it first and uses it to stab Clark.
During a Valentine's Day date with Lois, Clark is exposed to a new form of kryptonite know as Gemstone kryptonite that give him the temporary power of Persuasion unbeknownst to him at first. During this state Lois, Chloe, Emil & Zod are infected and response to Clark's power of Persuasion acting accordingly to his words. Clark uses this to his advantage in questioning Zod about his father's death to which Zod turns the tables on Clark pining the blame on Tess. Under the influence of Gemstone kryptonite Clark furiously attempt to seek vengeance against Tess for the death of his beloved father by placing her inside a ring of fire he created with his heat vision attempting to incinerate. Chloe uses Green kryptonite to weaken Clark temporarily which also removed the effects of the Gemstone kryptonite curing herself and Clark in the process.
Chloe steals funds from Oliver company to buy a massive arsenal of kryptonite laced weaponry in an effort to be ready should the kandorians ever find a way to obtain their powers. These weapons would at least give humanity a fighting chance to defend themselves from living in slavery. In Dr. Bernard Chisholm lab their are kryptonite laced nails on the operating table. When Zod is shot and at the edge of death Clark honors his father's last dying request to save Zod, by using one of the kryptonite nails to cut himself allowing a drop of his blood to heal Zod bring him back from the dead fully reborn as a true kryptonian with all his powers restored unbeknownst to Clark.
Tess conducts an experiment to test Zod in the process she discovers that he's obtain his kryptonian powers. When Zod grabs her by the neck and threatens to kill her for knowing his secret, Tess opens a secret compartment which contains kryptonite and it weakens Zod, who falls in pain to the ground.
John Corben is revived by scientists under the orders of Tess in a secret underground lab that Lois discovers is housing a supply of green and red kryptonite that scientists are performing many experiments on. Corben escapes and saves Lois life from the lab explosion. Later Clark returns to the very same lab and is infected with a large dose of Red Kryptonite in the form of red smoke. Under infection of Red-K, Clark turns against Chloe when he discovers she has vast arsenals of kryptonite storage weapons all over North America. Meanwhile, John's discovered one of Chloe's arsenals and uses some of the kryptonite bottles to refuel his heart. As he starts to get out of the truck, Clark arrives and is weakened by John's heart. Zod flies and arrives right afterwards, blowing up the truck, Corben survives the explosion and under the control of Tess & Chloe infiltrate the Fortress of Solitude and after an engaging confrontation with Zod & Kal freeing Corben of mind control Corben uses a shard of Kryptonite to stab Clark freeing him from his Red-K infection.
Tess confronts Zod at the Fortress with one pair of Green kryptonite laced brass knuckle in an attempt to prevent Zod from ruling earth in tyranny like he had in that alternate future she had witnessed. She begins to beat him severely until Zod managed to get a safe distance away from the kryptonite radiation and launches a counter attack against her for her treachery by incinerating half her face and body with his heat vision leaving her their to died. Until she is found and rescued by Clark.
Granny Goodness's female furies are using kryptonite to power up their weapons arsenal. When Clark rescues a little girl held captive by Granny in an effort to reprogrammed her into one of her loyal warriors. Clark encounters the leader of the furies known as Harriet who has razor sharp claws infused with kryptonite making her able to penetrate Clark's skin causing him to bleed. Also in the lair their's a fire pit with kryptonite subduing Clark's powers until he use his super breath to freeze a chain above the fire that's holding a lamp shield lined with lead to cover the kryptonite radiation restoring his powers before Granny Goodness has a chance to brainwash him into becoming her minion .
In a parallel universe in which Clark Kent's doppelganger Clark Luthor is a villain, Oliver set up a trap for his nemesis using the abandoned Watchtower window as a kryptonite solar weapon against Clark Kent unaware that he's actually the good counterpart from a different world . Clark is weakened by the kryptonite radiation and just when he's about to be killed by Oliver, The Lionel Luthor of that universe saves him only in turn to take out his own anger and frustration on Clark thinking he's his son by beating him. Oliver sees during the struggle that this isn't the evil incarnate Clark that he knows and he helps Clark by deactivating the kryptonite weapon allowing Clark Kent to heal and uses the mirror box to return to his world. Upon returning to his world, Clark sees Oliver, Lois and Tess are standing over him about to fire their kryptonite weapons. Clark tries to convince them that it's him and turns to Lois, who realizes that it really is him and they lower the weapons.
"Alexander" used kryptonite bullets when he tried to assassinate Martha in hopes that Clark would speed in and shield her from the bullet. He later pulled a gun on Clark and Tess, filled with the same kryptonite bullets.
Lionel used a piece of green kryptonite to incapacitate Clark and Conner. He then used the same piece to beat Clark and left it next to him, waiting for it to inevitably kill him, but Conner used his heat vision to destroy it.
TV Guide ComicElemental - Teenager Jacob Snell is exposed to a kryptonite dust cloud, giving him the power to control hailstones. After losing control of his powers, an explosion is caused. Afterwards he loses his powers and his memory of them.
Smallville #5 The Few, The Proud - Whitney is carrying around Lana's necklace for good luck. Some of his fellow soldiers playfully take it from him.
Smallville: Visions - Taking place during Hero, Jordan Cross has the kryptonite-laced gum, thus resulting in the temporary return of his powers. His friend Zach also has some gum, resulting in gaining superspeed. Clark destroys the gum in Chapter 5 with heat vision.
Lana's necklace appears in Trespass but it is clear not green similar to Hereafter when the only kryptonite that appeared in that episode was Lana's neutralized necklace.
When Metallo was shown in Prophecy, he still had his green kryptonite heart implanted.