Meteor freaks ('freak of the week')
72 episodes of Smallville carry this thread, 3d 0h in all — 0 of them are in The Essentials.
Arc membership is derived from each episode's own summary text, gated to the seasons the sources place each arc in. It shows where a thread is foregrounded, not every episode it touches.
In airing order

A bug-loving teen is infused with superpowers after a bizarre accident, and the boy sets out to steal Lana's heart and dispose of her current boyfriend, an intimidating jock who warns the "bug boy" to stay away from Lana. Meanwhile, Lex asks the Kents to cater a party he is throwing.

The Smallville High School football coach asks Clark to join the squad, something Jonathan fears may jeopardize the teen's secret and the safety of the other players. What Clark doesn't know is that the coach has some powers up his sleeve as well, and he's using them to cover up a cheating scandal involving his players. Elsewhere, Lex faces off against his father over business practices; and Lana quits the cheerleading squad.

After falling through the ice and nearly drowning, a teen finds that he cannot keep himself warm without extracting heat from an outside source---mainly other people. Meanwhile, Lex persuades Clark to ask Lana out on a platonic date.

Clark volunteers at a nursing home, where he meets a blind woman who claims that she can see the future---and that someone close to him will die soon. Meanwhile, another resident of the home regains his youth after falling into a lake lined with kryptonite, and he sets out to kill the descendants of jurors who convicted him of murder when he was young.

An overweight teen becomes excessively thin after eating vegetables tainted with kryptonite, but she also develops a voracious appetite for food---including human flesh. Meanwhile, Clark ponders what to get Lana for her birthday; Whitney gets a tryout for a college football team; and Lex learns some disturbing news about his health.

An old Kent family friend, who suffers from uncontrollably violent convulsions after working for Luthor Corp., shows up at the farm after accidentally killing a man in Metropolis. Meanwhile, when Clark's parents head to the city for a romantic getaway, the teen decides to host a party that soon gets out of hand.

A corrupt Metropolis police detective sees Clark stop an out-of-control bus barreling toward a homeless man, and the cop threatens to expose the teen's secret unless he does what the lawman wants. Meanwhile, a rich old flame visits Lex and asks him to reconsider his position in his father's company.

A teen whose family lives and works in the Luthor mansion has a crush on Lex, and her jealousy of the tycoon's new girlfriend brings forth vandalism by an invisible perpetrator. Meanwhile, Clark volunteers to work with Lana on a school blood drive after she and Whitney have a fight.

A crooked businessman who can get people to do whatever he wants by touching their hands sets out to buy the Kent farm so he can build an industrial plant in Smallville. Meanwhile, Clark and Lana argue over a physical confrontation between Whitney and a town hermit.

Chloe is seriously injured during a robbery at Lex's mansion that is perpetrated by three masked young men who can pass through walls. Meanwhile, Whitney's personal problems make him a target for the three bandits.

An incident from Lex's past returns to haunt him when a man he believed died in a shooting incident returns from the grave to ruin his reputation. Meanwhile, Chloe starts digging into Clark's adoption history.

Dr. Hamilton irradiates an extinct flower with meteor radiation, releasing an infection that causes uninhibited behavior, coma, and death... and Jonathan and Lana are among its victims.

A fall from a tall building embeds a kryptonite fragment into a man's arm, and he develops the ability to burn his victims to death with his bare hands. Meanwhile, Clark dreads going on a yearly fishing trip with Jonathan and he tells him so in a fit of anger.

Clark decides to run for class president after Pete nominates him, but the teen faces off against a candidate with the secret ability to control a swarm of killer bees. Meanwhile, a Metropolis newspaper reporter sets out to write an exclusive feature on Lex, against the billionaire's wishes.

Clark finally learns that Chloe has a crush on him and he begins to question how he feels about her. But his indecisiveness leads to her interest in another student, an artist with telekinetic abilities whose hands were damaged in a car accident.

Lex impulsively marries a woman two weeks after he meets her, unknowingly moved by her ability to control a man's mind by emitting a kind of pheromone mist. He's also unaware that she plans to kill him so that she can inherit his fortune. Elsewhere, Clark has trouble controlling his newest power---heat vision.

A teen who is kept locked in the basement of his parents' house during the day sneaks out at night and leaves love letters for Lana at her parents' graves. Meanwhile, Lionel Luthor hires Clark's mother as his personal assistant.

Family secrets abound as Martha goes behind Jonathan's back to ask her father for money after the family's bills pile up; and Lana finds pictures of her mother with another man that were taken after her parents were married. Meanwhile, a healthy high-school student dies of old age shortly after kissing his girlfriend; and Clark has a run-in with the new school principal.

Clark rescues a teenage mind reader from a laboratory where a maniacal scientist performs cruel cognitive experiments on the youngster. Meanwhile, Lex crosses swords with the corrupt mayor of Smallville over a potential business deal.

A Smallville honor student who can clone himself at will kills a teacher to avoid a bad grade, then develops a romantic interest in Chloe and Lana. Meanwhile, Martha feels guilty about her career choices after Jonathan is injured in an accident on the Kent farm while she is at work.

One of Clark's former adversaries returns to Smallville and causes a rift between Lana and Clark. Elsewhere, Lex accuses a woman he's dating of spying on him for Lionel Luthor.

Lex hires goons to plant listening devices in his father's Metropolis office, but things go awry when the thugs decide to rob the tycoon's vault instead and end up taking two hostages: Lionel Luthor and Martha Kent. Meanwhile, Lana learns that her biological father's wife has agreed to meet with her, but the encounter proves to be a tense one.

Lionel Luthor is shot by an unknown assailant and Jonathan Kent is arrested for the crime after the police find him with a gun and a bottle of tequila. Meanwhile, Lex does some digging of his own and begins to suspect that someone else pulled the trigger, but his reluctance to share this information leads to a clash with Clark.

A strange parasite invades Pete's body and feeds on the teen's adrenal glands, causing him to shake off his inhibitions and engage in wild and dangerous behavior. Meanwhile, Clark gathers his courage and asks Lana for a date, which she eagerly accepts.

Lex finds his long-lost brother, Lucas, and tries to persuade his sibling to help him stage a financial coup against their father. Unfortunately, Lex's plan backfires. Meanwhile, Clark applies for a position at Lana's coffee shop.

Martha is hospitalized after becoming seriously ill from exposure to kryptonite spores in the Kent's storm cellar, and Jonathan learns there are complications. Meanwhile, Lex's girlfriend is offered a lucrative position at a hospital far away from Smallville.

Clark thinks an awkward new student who claims to be an extraterrestrial might be telling the truth after he sees the teen start a fire with his eyes and heal a sick horse with his touch. Meanwhile, Lex's lovelife heats up when he asks Helen to move into the mansion with him.

Clark is arrested and his family faces a civil lawsuit after the teen defends Lana by hurling an unruly college student onto the hood of an oncoming police car. Elsewhere, Helen's former boyfriend arrives in Smallville and causes trouble for Lex by filing a false assault charge against him.

Clark witnesses a popular Smallville baseball player steal a shipment of refined kryptonite from a LuthorCorp truck to enhance his athletic abilities. Meanwhile, Lana's relationship with her father improves, while Clark's friendship with Chloe deteriorates.

Lana thinks she sees the ghost of a childhood friend who died years before when she's visited by a 10-year-old girl, so Clark sets out to find a logical explanation for the incidents. In other developments, Lex prepares for his wedding by meeting with an event coordinator; and Jonathan begins building a crib in anticipation of the new baby.

A teenager is hunting down Smallville residents who were altered by kryptonite rocks, and he inadvertently discovers Clark's abilities when the boy of steel saves Lex from being the hunter's next victim.

Clark has a dream that his new neighbor, whom he hasn't met, is being haunted by a mysterious demon-like figure.

The future Daily Planet editor-in-chief Perry White, who's working as a tabloid TV reporter researching meteor phenomena, suspects Clark has super abilities after he's rescued by the teen. Meanwhile, Clark has trouble controlling his powers.

After Clark sees visions of a 40-year-old murder involving Lana's great-aunt and great-uncle, he begins an investigation into the past that reveals secrets about his Kryptonian family history.

Lana's sudden attraction to a teen with magnetic powers arouses Clark's suspicions that the boy is able to control her mind. Elsewhere, Lex confronts Chloe about her past investigations of his father.

Clark loses his sight and gains superhuman hearing, which he can't control, when he attempts to stop a jewelry-store robbery involving a teen with a powerful scream. Also, Clark learns that Chloe did research on him for Lionel; Pete is kidnapped.

Clark and Lana unwillingly attack Chloe on separate occasions after being hypnotized by subliminal e-mail messages. In other events, Lana grows suspicious of Adam after he reveals his unusually adept martial-arts skills.

Clark befriends a teen who has uncontrollable premonitions about the future whenever he comes into contact with other people. Elsewhere, Lana grows more suspicious of Adam after he has a series of violent dreams.

Pete gets in over his head when he gets involved in illegal street racing using Kryptonite-fueled cars; Lana confronts Adam about his mysterious past; and Chloe continues to secretly investigate Adam's background.

A student who has the ability to teleport herself---as well as anything she touches---develops a crush on Clark after he reveals his own powers while saving her from an elevator mishap. Elsewhere, Lana learns Adam has been keeping a daily log on her and Clark and threatens to have him evicted.

Clark befriends a teen whose brother is mysteriously raised from the dead after succumbing to liver disease. Also: Jonathan learns he must undergo triple-bypass surgery.

Clark gets a panicked phone call from Lana in which he hears her being killed. When he finds out the call is from the future, he tries to change the present, hoping to alter fate. Elsewhere, Lex tells his dad he wants to be in charge of the "resurrection serum" project.

Lionel makes a deal with Dr. Virgil Swann, hoping to uncover the secrets behind the Indian cave drawings. Elsewhere, Jonathan continues to struggle with his own mortality; and Lex works as an informant for the FBI against his will.

A chemical accident at the LuthorCorp plant gives Chloe the ability to make people tell her the truth. When Lionel learns of Chloe's new power, he tries to exploit it by forcing her to uncover Clark's secrets.

A Kawatche grad student gets superpowers similar to Clark's when he picks up an ancient knife found in the Indian caves. Elsewhere, Lana and Chloe plan a surprise birthday party for Clark at Lex's mansion; and Lex wants to sell the Talon.

Clark tries out for football again and learns that Jason is the new assistant coach---but Clark doesn't know Jason is also Lana's boyfriend. Meanwhile, a student gets a bizarre makeover with a dangerous side effect that gives her the power to alter the way others see themselves; Lois enrolls at Smallville High for a semester after she finds out she's a few credits shy of graduating; and Martha takes a managing job at the Talon.

When two cheerleaders develop a love potion that arouses feelings of extreme devotion and jealousy, it causes a football player to attack Jason for "checking out" his girlfriend and prompts Chloe to hit on Clark. Also: Clark is made starting quarterback, a promotion that doesn't sit well with his new teammates; and Lex donates new uniforms to the team, but Clark is put off by the gesture, which he takes as an attempt to buy back his friendship.

Clark accidentally injures another player when foreign-exchange student Mikail Mxyzptlk uses a form of telepathy to make him trip during a big game. As a result, Jonathan wants Clark to quit the team before he hurts anyone else, and Jason suspects Clark is using steroids.

Lana, Lois and Chloe are possessed by the spirits of witches who were burned at the stake in the 17th century. Later, the girls crash a surprise party for Chloe at the Kent farm and use a spell to turn the event into a raucous affair. Making matters worse, a Princeton recruiter visits Clark the night of the party.

Lana meets Jason's mom and is surprised to discover that she looks like a woman from a dream she had about Isobel, the 17th-century witch who possessed her. Elsewhere, Lex is the prime suspect in a murder case after he wakes up next to the body of a slain woman.

The town's residents are infected by a toxin that causes unconsciousness and horrific nightmares when the LuthorCorp plant loses control of the dangerous substance. Meanwhile, Lionel's conviction is overturned, but he feels he deserves to stay in prison.

Lois is arrested for severely injuring a Metropolis University football player who harassed her. Meanwhile, Clark visits the school on a recruiting trip and discovers scandalous activity involving the team; Jason takes Lex up on his job offer, which entails spying on Lana and Genevieve.

Clark takes in a dog with superpowers after Lois accidentally hits the pooch with her car. While looking for its owner, he discovers the dog was part of a LuthorCorp experiment and was being used to commit crimes. Elsewhere, Genevieve is revealed to be the person who helped free Lionel from prison.

Lois's younger sister, Lucy, arrives in town, and Clark learns that she has a shady past when he catches her stealing money from the Talon's register. Also, the ancient stone is taken from Lana's apartment, and Jason suspects Lionel.

On the night before the prom, a popular student crashes her car into a kryptonite-filled ravine and her spirit ends up taking over other people's bodies. Elsewhere, the body of Dr. Swann's assistant, Bridgette Crosby, is found in a shallow grave on Lex's property, and Jason accuses Lex of killing her. Lifehouse performs at the dance.

Clark's entire memory ends up getting erased when he confronts a thief who has a kryptonite-based ability to wipe out people's short-term memories. As Clark learns about his life, he's shocked to discover that he has superpowers.

Lana and Clark take care of a baby they find in a crater and are shocked when he ages seven years right in front of their eyes. They then turn to Lex for help, hoping LuthorCorp labs can find a way to curtail the child's growth. Elsewhere, Genevieve confronts Lionel about the missing sacred stone.

A teen who has the power to turn people into stone wants to stay in high school forever, so he keeps students captive in a fake school that's built to look like Smallville High. Elsewhere, Genevieve and Jason threaten to kill Lex if Lionel doesn't give up the sacred stone.

Clark hopes Kara will keep a low profile, but three meteor-infected girls want to use her as part of their scheme after one of them sees Kara's special powers.

Lex employs Dr. Curtis Knox to cure the meteor-infected, and Chloe ends up a patient. Meanwhile, John Jones warns Clark that his cousin Kara should not be trusted.

Clark saves the life of a starlet on a film shoot in Smallville when a stunt car's brakes fail, but what happened was no accident. Meanwhile, Lionel finds himself the victim of a surprising captor.

In the process of trying to get the crystal back, Kara is captured and sedated with a kryptonite serum; Clark follows and tries to release her, but not before the serum has caused both to have a vision of Clark's mother.

Lana absorbs Clark's powers and uses them to go after Lex, first trying to expose his secrets in the Daily Planet, then moving on to a more personal level.

Clark makes a huge mistake when he releases Lara from the crystal, because Zor-El is also released. Elsewhere, the relationship between Lois and Grant heats up.

Clark comes home and tells Lana that Kara has vanished, and that they should work together to stop Lex; and a man named Adrian, infected with an alien substance, plants a bomb on Chloe, who then confesses to Jimmy that she is a meteor freak.

Clark is frozen in the Fortress and Bizarro takes over his life, starting with Lana, who shares information about Brainiac. Elsewhere, Grant reveals he is a clone of Julian, and Lex is shocked at his father's reaction to this revelation.

Lois trails Lex to Detroit, where he has found Kara suffering from amnesia. A busboy obsessed with Kara shoots Lex so he can't take her away, and holds Kara and Lois captive. Chloe finds Lex and offers to heal him, but Clark will not let her.

Former Smallville resident Pete Ross, now a roadie for the band OneRepublic, accidentally chews kryptonite-laced gum and gets superpowers. Clark and Chloe try to warn him about the effects, but Lex finds out and uses Pete for his nefarious schemes.

Kara teaches Clark how to fly to help him fight against Brainiac, but Brainiac seems to be a step ahead of them.

Clark searches for Brainiac, who is the only one who can reverse Lana's condition; Chloe accidentally sets off alarms as she hacks into government computers while trying to find info to help Clark; the Department of Security threatens Jimmy with jail time unless he helps them arrest Chloe, while Lex offers to help clear Chloe, but only if Jimmy agrees to be in his debt.

Clark, through a series of messages sent by Kara from Krypton, discovers what Earth would be like had he never arrived: Jonathan is still alive; Lex is the president; the Luthors have raised Kara; Lana is happily married; and Chloe and Lois are ace reporters.

A cloaked stranger attacks Lex, leaving him with Kryptonian symbols carved on his chest. They were intended as a message for Clark, who investigates with Chloe and learns that one member from Veritas is still alive and hiding in a church.