A freak of the week (or FOTW) refers to a villain having superhuman powers who is prominently featured in a Smallville episode, typically appearing only in a single episode. A FOTW villain is often a "meteor freak", or temporarily metahuman, as a result of kryptonite-inspired powers. The "freak of the week" formula was heavily used in Season One.
The typical formula for a "freak of the week" episode has three key elements:
The freak of the week gains kryptonite-inspired powers (either from one of the meteor showers or from a more recent exposure to kryptonite).
They become psychotic and use their powers to attempt to somehow hurt or terrorize someone else.
The freak of the week is eventually subdued by a hero (usually Clark Kent), and either end up somehow dying or, alternatively, are institutionalized in Belle Reve. Occasionally they lose their superpowers and go back to being normal human beings.
Jeremy Creek, aka The Electric Scarecrow, was a former Smallville High School student, who fell into a coma during the meteor shower. He awoke without having aged and had achieved the ability to manipulate electricity. He lost this ability in the end and returned to normal when he electrocuted himself.
Greg Arkin, aka Bug Boy, was a Smallville High School student who collected insects, was bitten by kryptonite-infected bugs and got himself abilities of insects. After having abducted Lana, he fought with Clark and was crushed by a falling machine part.
Coach Walt Arnold, aka The Hotheaded Coach, a coach at Smallville High School, used kryptonite rocks in his sauna and thereby got the ability to provoke fire by his will. When confronted by Clark, he burned himself to death.
Sean Kelvin, aka The Heatsucking Horndog, was a Smallville High School student, he fell into a frozen lake in which meteor rocks were accumulated. He the had to drain heat from other bodies or objects to keep himself warm. He died when he was thrown by Clark into a pond which instantly froze.
Harry Volk, aka Harry Bolston was an inhabitant of the Smallville Retirement Center, he fell into a basin with meteor rocks in, along with his electric wheelchair. The meteors and the electricity mixed into his DNA and he regained his youth. He started to kill children of the jurors who had found him guilty at his trial. He died as he returned to his original age.
Jodi Melville, aka the Fat Sucking Vampire, was a fat Smallville High School student who reduced her weight drinking vegetable shakes which were, however, meteor-rock infected and made her so hungry that she had to suck the fat out of other people. She was saved by Clark from committing suicide and taken to Metropolis General Hospital.
Jeff Palmer, aka The Invisible Man, made a cream from meteor rock mutated roses rendering him invisible. After trying to drown Victoria Hardwick, he was overcome by Clark and taken away in an ambulance in need of some "serious therapy."
Bob Rickman, aka The Persuasive Salesman, was trapped in his car during the meteor shower and thereby had got the ability to manipulate people by his handshake to do anything he wanted, even to commit suicide or murders. At the end, his former business partner Kyle Tippet who hade the same abilities made Bob shoot himself to death.
Eric Summers, aka Superboy, temporarily absorbed Clark's powers when both were struck by a lightning in the presence of meteor rocks. After Clark succeeded in getting his powers back from him, Eric was taken to Belle Reve and reappeared in episode 3x09.
Wade Mahaney, Derek Fox and Scott Bowman, aka The 3 Intangible Jocks, used kryptonite tattoos which made them temporarily able to walk through walls as long as the tattoo lasted. Wade was killed by a falling car after his tattoo had faded, and Derek and Scott were taken into custody.
Tyler Randall, aka The Reaper, fell out of a window onto meteor rocks and died. He came back to live and got the ability to turn living beings into ash. At the end, he turned himself to ash from remorse for his deeds.
Sasha Woodman, aka The Queen Bee, a student at Smallville high, was stung by bees infected by kryptonite and got the ability to command swarms of bees. At the end, she fell into a coma when she was stung by her own bees. She was taken to Belle Reve and reappeared as cured in episode 7x04 where she was killed by Dr. Knox.
Justin Gaines, aka The Pickup Artist, a student at Smallville high, lost the use of his hands due to a car accident. He then developed the power of telekinesis to compensate for the loss of the motor skills in his hands. After being defeated by Clark, he was admitted into a psychiatric ward.
Desirée Atkins, aka The Black-Widow, a Smallville High teacher, could breathe meta-human pheromones from her mouth to manipulate human males. She first manipulated Lex to marry her, and then Jonathan to kill Lex in order to inherit his fortune. She was overcome by Clark and probably taken to prison.
Steven Hamilton, a scientist, had got seizures from making experiments with kryptonite. He stole the spaceship that Pete had found in the field and abducted Pete to learn who's ship it was. When Clark freed Pete, Hamilton died from his seizures which were intensified by a kryptonite containing liquid dropping on his head.
Byron Moore had been given drugs from LuthorCorp which had the side effect that he transformed into a beast having super strength each time he got into the sunlight. When he tried to kill Lionel for revenge, Clark pushed him down a well where it was dark. Byron changed back to normal and was taken to the hospital where he was kept under a special light.
Chrissy Parker, aka Youth Sucker, had the ability to absorb the life energy from the people she kissed whereby she stayed young over more than a hundred years. She kissed two students who died, but was prevented from kissing her third victim by Clark. She thereupon rapidly aged herself and died.
Ian Randall, a Smallville High student, could split into two different persons. He used this ability to date Lana and Chloe simultaneously. When they found out, he tried to kill them both, but Clark saved them. Ian was taken to Belle Reve where he was killed in episode 3x09.
Kyla Willowbrook, a lovely Kawatche teenager with the ability to transform into a wolf, developed a romance with Clark. When she threatened Lionel in wolf form to make him leave the Kawatche Caves untouched, Clark intervened and she jumped out through a closed window and died from the cuts caused by the glass splinters.
Tina Greer from episode 1x04 escaped from Belle Reve and returned to Smallville impersonating first Whitney and then Clark in order to be with Lana. In a fight with Clark, she died when she accidentally impaled herself on a wooden pile.
Eric Marsh, a smallville high student and baseball player, gained super strength from inhaling liquified kryptonite made from bars of kryptonite he and his companians had stolen from LuthorCorp. When they noticed that Clark had discovered their secret, the tried to kill him, but were overcome by him in the end and arrested by the police.
Emily Dinsmore, a clone of a childhood friend of Lana, had super speed and super strength and could walk through solid walls. When she discovered that the original Emily had died in an attempt to save Lana from a river, she pushed Lana from a bridge into the river. Lana was saved by Clark, and Emily was taken into custody by Lionel and reappeared in episode 3x21.
Sarah Conroy had fallen into a coma at a car accident and was kept asleep by her uncle with intravenous drugs. Due to an exposure to meteor rocks during the car accident, she had got he ability to manipulate other person's dreams. After Clark prevented her uncle from giving her drugs, she woke up.
Seth Nelson, a Smallville High student, developed magnetic control over metal and mind, when he was subjected to an MRI treatment with pieces of meteor rock in his head. He manipulated Lana to leave the town with him and finally fell into a coma when Clark used electricity to break his magnetic powers.
Nathan Dean could shriek massive sound waves and used this ability to help his master Walt Masterson commit robberies. Dean was killed when a pile of cars in the junkyard fell upon him loosened by his soundwaves, and Masterson went to prison.
Molly Griggs, a former MIT student, was treated in Summerholt Institute where she developed a mind-control program by which she could manipulate the mind of other people via e-mail. After she tried to make Clark, Lana and the Kents kill Chloe, she was taken into custody by Lex who promised her real help.
Alicia Baker, a Shmallville high student, had got the ability to teleport during the meteor shower. She learned Clark's secret and fell into love with him. When she tried to kill Lana, she was overcome by Clark and taken to Belle Reve from where she was released in episode 4x11.
Emily Dinsmore from episode 2x21 escaped her confinement, captured Lana and locked her into a glass cell to be always near her. When Lana tried to escape, Emily wanted to kill her with gas. She was overcome by Clark and taken to Belle Reve, from where she escaped and was never seen again.
Trent MacGowen, is a former patient from Belle Reve, had the ability to morph his body or parts thereof into metal and use them as arms. He was ordered by Lionel to kill Chloe, but was overcome by Clark and fell into a trough filled with molten metal.
Abigail Fine, a Smallville High student, was exposed to a kryptonite-powered plastic surgery by her mother Elise Fine. The operation had the side effect to provoke violent hallucinations in everybody she kissed. It is left open whether she finally returned to normal.
Mikhail Mxyzptlk, an exchange student form south-east Europe, could control other people's action by murmuring words and used this to cheat at sports wagering. Clark and Chloe succeed in blocking this ability by ultrasonic waves, and Lex took Mikhail into custody at Level 33.1.
Tim Westcott was able to dissolve his body and the clothing he is wearing into sand. He tried to kill Lana and Jason and framed Alicia Baker as being the attacker. When he finally killed her was confronted by Clark, he attacked him in form of a sandstorm, but was forced back to his human form by Clark's heat vision and presumably taken to prison.
Geoff Johns, a football star at Metropolis University, could paralyze people by touching them, and used his powers during the football matches. When Lois found out that he payed other students for urine samples to hide his secret, he tried to kill her, but was stopped by Clark.
Dawn Stiles, a Smallville High student, fell with her car into Carlton Gorge, which was full of meteor rocks. While her body was in a coma, her spirit had the ability to travel out of her body and to possess other people. When she possessed Chloe and tried to put the school on fire, she was stopped by Clark.
Brendan Nash, a Smallville High student, could turn people into wax. He did not want school to end, kidnapped Chloe, Lana and other students and placed them into an exact copy of a part of the Smallville High School built in an abandoned factory. When he tried to turn Clark into wax, his powers reflected to himself, and he fell and shattered.
Tommy Lee, who had the power to control electricity, and the Twins, who could generate a force field, broke out from Belle Reve and took the Kents hostages. Clark, who at this time was stripped off his powers, succeeded in overcoming Tommy by switching off the house's electricity, and the three were taken back to Belle Reve.
Buffy Sanders had been bitten by meteor-infected bats and turned into a vampire. She became the leader of the Tri-Psi sorority at Metropolis University which she made a sorority of vampires. She made Lana join the sorority and turned her into a vampire, too. When Buffy tried to kill Clark, she was killed by Lana.
Gretchen Winters had been murdered and hidden behind a wall of the Talon. From a kryptonite-gemstone bracelet, her spirit got the power to possess Chloe when she and Clark found the corpse. She made Chloe search for her murderer, Michael Westmore. She then took possession of him and made him kill himself.
Tyler McKnight had received the ability to control glass with his mind in the 1989 meteor shower. He was brought to Belle Reve, but released for good behaviour. He kidnapped his daughter, Maddie Van Horn, killing her foster mother and an advocate. He was finally overcome by Maddie and brought back to Belle Reve.
Graham Garrett had the ability to render himself invisible und used this to work as a contract killer. When Clark saved his live, Graham wanted to thank him by killing Lex, believing that Lana would then return to Clark. In the attempt, however, he was hit by a bullet randomly fired by Lana and died in the hospital.
Duncan Allenmeyer, a former school friend of Lex, stayed in a vegetative state after a car accident. A medicine made from meteor rock gave him the power to astral-project out of his body and use psychokinesis to attack those responsible for what happened to him. When he shot an EMP arrow at Oliver, Clark intercepted the arrow. Duncans astral body was destroyed by the EMP and he died.
Bronson had got the ability to travel to different frequencies in the 2005 meteor shower. He kidnapped Lex and Lana and took them to another frequency. When he threatened Lana, he was stabbed by Lex. Jimmy succeeded to tune into the right channel and bring Lana and Lex back.
Jed McNally got the ability to move underground in the 2005 meteor shower. He held immigrants as slaves on his farm. When someone tried to flee, he used his powers to draw him underground. When McNally attacked Javier Ramirez, who had escaped from the farm, he was knocked unconscious by Clark and then taken to Level 33.1 by Lex.
Tempest Drake, Tyler Crenshaw, and Carly Meadows, the Weather Girls, could control the weather elements heat, cold, and wind. They tried to steal a tresure hidden in Smallville. Carly was killed by Tyler when cheating the others. When Clark tried to stop them, Tempest created a storm which blew green kryptonite on him. Clark was rescued by Kara, and Tempest and Tyler were arrested.
Bette Sans Souci had the ability to project energy blasts from her eyes. She blew up of a bus and blamed Tommy Walker for it, whom she later murdered. When Chloe found out her secret, she tried to kill her, too. Clark deflected the blast back on herself, and she was arrested. On her way to Belle Reve, she was convinced by Tess to join her team of metahumans.
Randy Klein could transform into a shadow creature having super powers. When a series killer appeared in Metropolis, Randy pretended to be the killer so as to acquire the attention he always wanted but never got. He was arrested, but then freed by Eva Greer who knew he was not the real killer and offered him to join Tess's team of metahumans.
Sebastian Kane, a former captive of Black Creek, had the ability of reading minds through touch. Tess used him to learn whether Lois had stolen the Crystal of Knowledge from her. When Sebastian learned that Lois knew his past, he tried to kill her, but was knocked out by Clark. By the touch, he learned Clark's secret. When he recovered in the hospital, Chloe who was possessed by Brainiac overloaded his brain so that he died.
Linda Lake from episode 6x10 reappeared and blackmailed Clark to make her the exclusive reporter of the Blur. Clark refused and let Lois publish an article about his true identity and origin. Linda then publicly stated that Clark was the murderer of Lex and planned an alien invasion. To prevent Linda from reappearing, Clark used a Legion ring to travel into the past and let Linda be arrested for the murders she had committed. Linda then tried to blackmail Davis, but was killed by him.
Tess used the team to hunt down Doomsday in order to make Clark kill him. Nathaniel was killed by Doomsday, Eva and Leslie by Tess when they disobeyed her. Rudy and Bette were arrested and later freed by Rick Flag to join his Suicide Squad.
In Season Eight, although the "freak of the week" formula was used in Identity, this was used for the B-plot, while the A-plot focused on Clark trying to hide his identity.
Four series regulars have had FOTW-style episodes where they temporarily became metahuman and then followed the "freak of the week" formula. These included Whitney Fordman in Season 1 (he gained intangibility powers from kryptonite tattoos), Chloe Sullivan in Season Three (she gained truth powers from kryptonite-based truth gas), Lana Lang in Season Five and Season Seven (in Season 5, she became a vampire after being bitten by a metahuman vampire and, in Season 7, she gained Clark's powers after being struck by lightning while near kryptonite), and Pete Ross in Season 7 (he gained elasticity powers from kryptonite-contaminated chewing gum). All of their personalities changed while possessing powers, and all of them reverted after losing or giving up their powers.