At a young age, Sam and Dean Winchester witnessed the unexplainable death of their mother, which in turn led their father to teach them skills which could be of use in the search for whatever it was that took her life. Years later, while attending Stanford University, Sam finds himself brought back into the paranormal world by his older brother, who has now come to tell him their father has mysteriously disappeared. The two hit the road to find him and are soon sidelined in a small town where the spirit of the "Woman in White" is ready for a fight. 

After following instructions found in their dad's journal, Sam and Dean pose as park rangers to help a brother and sister search for their lost sibling, who the Winchester brothers believe may have been taken by a Wendigo. 

Dean learns about a mysterious drowning victim in Wisconsin. The brothers come to believe that a spirit is haunting the lake, causing this and other drownings. They befriend a boy whose father has drowned, and his mother (played by Amy Acker.) 

Dean and Sam get a phone call about a demon which manifests itself through those with psychological issues and causes planes to crash. Dean is forced to face the demon aboard a plane, and face his fear of flying. 

Dean and Sam go to Toledo, Ohio, to investigate the mysterious death of a man who lost his eyes. They learn that Bloody Mary is haunting the town through a mirror on which a murder victim (named Mary) attempted to write the name of her killer before dying. 

Sam's college friend Zach has been arrested for murdering his girlfriend in St. Louis, Missouri. They visit Zach's sister, Rebecca, and help her investigate the murder. They discover that the real culprit is a being with shapeshifting abilities, who takes the form of Dean. 

Dean and Sam investigate the death of a student at a college. The student's girlfriend says the attacker was invisible. More attacks occur, all connected to the girl. They discover that Hookman is behind the killings, and that she is unknowingly summoning him. 

Dean and Sam check out the mysterious death of a construction worker on a new housing development. Soon the town is invaded by swarms of deadly bugs, which they originally suspect are being controlled by someone, but the cause turns out to be an Indian curse. 

Sam has nightmares of their old home, and the brothers return to Lawrence, Kansas to investigate. They discover that a new family has moved into the home, and enlist the help of their father's psychic friend, Missouri, to rid the house of its angry poltergeist. 

After receiving a tip from their father, Sam and Dean travel to Rockford, Illinois to investigate the haunted Roosevelt Asylum. An evil force inside causes Sam to lose his sanity and attack his brother. 

Sam and Dean investigate the disappearances of young couples in a rural Indiana town. They have a falling out, and split up. The scarecrow is a Vanir which protects the town at a price. A dark force is against the Winchester family. Sam meets Meg. 

While battling a creature, Dean gets electrocuted and his heart is damaged. Sam searches for a way to save him and believes he may have found an answer; a preacher who heals the incurable. However, Dean and Sam discover that the preacher is getting help from a reaper. 

Dean is contacted by his first love Cassie (Megalyn Echikunwoke), who asks him to come to Cape Girardeau in Missouri to investigate a string of racially motivated murders. Each murder is linked to a mysterious truck that seems to have no driver and leave no tracks. 

Sam has a premonition that a man was killed in Saginaw, Michigan, but the murder looks like a suicide. They fail to find anything supernatural until they meet Max, who has been using his telekinesis power to kill his abusive family members. This is the first episode where Sam is seen using his powers of telekinesis. 

Sam and Dean head to Hibbing, Minnesota, where a young boy (Ryan Drescher) witnesses a man vanish into thin air. While investigating, Sam is abducted. Dean is left to team up with a female cop. They are stunned when the kidnappers are human. 

Sam and Dean run into Meg while investigating a death in Chicago. They discover she is behind the murders, and Meg unleashes shadow spirits on the brothers in an ambush. Sam and Dean realize the trap isn't for them, but for their father. 

They investigate a house haunted by the ghost of Mordecai, a man who reportedly killed his six daughters during the 1930s. The brothers discover a website run by paranormal investigators and realize the town is unknowingly using it conjure up a tulpa. 

Sam and Dean investigate a small town where children are falling into comas. The brothers discover that a shtriga is stealing their "life force." Also, Dean recalls a past mistake that almost cost Sam his life at the hands of the very same witch. 

Sam and Dean investigate a painting; everyone who has ever bought the painting has been murdered, and they race to discover how the portrait is causing the deaths before it can claim its next victim. Also, Sam finds a possible love interest! 

A vampire hunter is murdered, and John shows up to solve the case. John discovers the vampires have taken an antique gun, the Colt, which, when loaded with its accompanying bullets, has the power to kill any living or supernatural being. The three then go after the Colt. 

Sam has a vision of a family being attacked by the demon, so he, Dean, and John head off to save the family and nearly kill the demon using the Colt gun. Meg calls them and John meets Meg to deliver a fake gun, while the boys are left to deal with the demon. 

On a mission to save their father from Meg, Sam and Dean lure her into a special demon trap and exorcise the demon from her body. They save John but on the way to the hospital they get into a car crash that is not as it appears. It ends with the camera staring at the bloodied bodies of the Winchesters. 

The series picks up where it left off, and the Winchesters are taken to a hospital. Dean is in a coma and a grim reaper is trying to take his soul, later Dean learns that by refusing to move on he might become in a spirit just like the ones the fight. Sam tries without success to save his brother, but John makes a deal with The Yellow eyes Demon to save his son's life in exchange of his own life and his much appreciated Colt. 

Sam and Dean burn their father's body, and the brothers meet fellow hunters Ash, Ellen, and Jo. Sam and Dean track a Hindu demon called a Rakshasa that disguises itself as a clown to trick children so it can kill and eat the parents. 

The brothers team up with Gordon, a hunter, to kill vampires. But Sam learns that the vampires Gordon is hunting are reformed, surviving only on cow blood. The brothers find themselves in a role-reversal, protecting vampires from one of their fellow hunters. 

Dean and Sam meet Neil Levine, a heartbroken college kid who uses necromancy to bring back his crush from the dead. But she returns as an angry zombie, bent on killing her boyfriend and the girl he cheated with. 

The brothers meet Andy Gallagher, a modern-day hippie near Sam's age with the ability to control minds. But he attracts attention when people start committing suicide after receiving mysterious cell phone calls. 

Sam and Dean investigate the brutal slaying of blonde women from an apartment building. The spirit responsible is the ghost of H. H. Holmes, America's first serial murderer according to the Winchesters. Jo follows the Winchesters on their hunt, getting captured by the ghost. 

The Winchester brothers begin investigating the mysterious death of a lawyer and his wife, but when the local police look into the boys' records, Dean ends up behind bars for murder. Linda Blair guest stars. 

Sam and Dean try to help a man who has sold his soul to a demon to save the life of his terminally-ill wife. The same demon attempts to seduce Dean by trying to convince him to trade his soul for his father's. She claims John is now suffering in Hell for saving Dean. 

Sam and Dean go to a town called Rivergrove after Sam has a vision. They think demons are trying to wipe out the entire town from the inside out. Sam gets cut and possibly infected. Sam turns out to be immune to the virus, and the virus itself seems to have been made for the purpose of testing him. 

Dean reveals the secret John told him at the beginning of the season, causing a distraught Sam to leave Dean in search of answers. Sam meets Ava, a psychic who has had a vision of Sam's death. Dean discovers Gordon is after Sam and races to find his brother in time to save him. 

Sam and Dean investigate a town where several people have mysteriously died and the trail leads to a young girl who lives at an inn with her mother, and whose imaginary friend may be responsible for the deaths. 

After Sam and Dean are told recent crimes have been committed by a half-man, half-robot, they immediately discover that a shape shifter is actually responsible for the thefts, and set off to a local bank, hoping to catch the shifter before he does any more harm. 

Sam and Dean investigate a case where people who have committed murder claim that an angel told them to do so. The boys are skeptical until Sam sees the angel for himself. 

Sam has been missing for over a week when Dean finds him covered in blood with no memory of what has happened. 

Sam and Dean call on fellow hunter Bobby (Jim Beaver) for help with violent occurrences on a college campus, but Bobby has suspicions about both the culprit and the brothers' escalating feud. 

Sam and Dean attempt to help a woman named Molly (Tricia Helfer), who is being stalked by a farmer who annually haunts a highway and kills someone. 

Sam and Dean are on the trail of a werewolf but their only lead is a woman (Emmanuelle Vaugier) whose former boyfriend has been stalking her, and Sam finds himself falling for her. And then having to kill her after discovering she is a werewolf. 

Sam and Dean are drawn to a studio in the process of creating a horror movie. When a crew member is found dead on the ceiling by one of the main actors, the Brothers feel that they may be on a case similar to that of Poltergeist. 

Sam and Dean allow themselves to be arrested in order to investigate a series of murders inside a penitentiary. However things get complicated when FBI agent Henricksen shows up to take over their case. 

Dean is attacked by a Djinn... and finds himself in a new reality where his mother and Sam's girlfriend, Jessica are still alive and a mysterious woman holds the key to everything. 

Sam and other "special children" are abducted by the Yellow-Eyed Demon ( Azazel )and taken to a ghost town, where the ultimate battle must start. 

After the fight between Jake and Sam, Dean has to deal with the repercussions of his interference. The hunters are about to be taken down by the Demon and his minions when help arrives from someone unexpected. 

Bracing themselves for the possibility of an apocalyptic war, Sam and Dean realize they have an enormous task of hunting down the hundreds of demons that escaped from the Devil's Gate. With only a year left to live, Dean decides to live life to the fullest and exhibits a carefree attitude that troubles Sam, who is trying to find a loophole in the deal. Bobby tells the brothers about a sighting in Nebraska, that turns out to be seven demons that are the actual manifestations of the Seven Deadly Sins. 

Sam and Dean track down changelings that are pursuing mothers and their children. A boy they protect bears a strange resemblance to Dean, which at first makes Dean uncomfortable because he once had a one-night stand with the boy's mother Lisa. Sam learns more about his familiy roots and is offered a possible way to save Dean via a demonic proposition. 

Word continues to spread of the Winchesters and the opening of a devil's gate, with them to blame. The Winchesters suddenly find their luck rising after finding a rabbit's foot. Gordon's instincts may condemn Sam, Sam is kidnapped by a mentee of fellow hunter who admires Gordon and brutally beaten. Sam swears that his past supernatural abilities are gone, but he is ignored because the hunter believes he is on a mission from God. While looking for Sam, Dean spars with a thief named Bela and, luckily, gains the upper hand - for now. 

Sam and Dean investigate a rash of violent deaths in Elizabethville, Ohio, a once-sleepy town that has been turned into a haven for gamblers and drinkers. Dean discovers demons have infiltrated Elizabethville and are using their powers of persuasion to make the townspeople succumb to their basic instincts. Meanwhile, Ruby helps Bobby rebuild the Colt from scratch and stuns him with some news. 

Fairy tales come to life when the brothers investigate Callie, a young girl who seems to personify Snow White. Poisoned by her stepmother and trapped in a coma, the spirit becomes angrier as more time passes. Callie's father visits her constantly, reading her original Brothers Grimm stories and unknowingly inspiring her carnage. After putting her spirit to rest, Sam meets the crossroads demon to "make a deal" - either release Dean from his bargain or die. The demon says that she doesn't have the power to break the deal and only her boss has that ability. She then taunts Sam that letting Dean die will be good for Sam. After a moment's contemplation, Sam shoots her between the eyes with the Colt. 

Dean and Sam visit a woman, Gertrude, whose niece may have been drowned by ghosts from a sunken ship, only to find that the woman is well aware of that possibility and their cover has already been blown by Bela. Without missing a beat, Dean smoothly goes along with the woman's realization. Later, Bela and Dean struggle for the upper hand and Sam tries to avoid Gertrude's while they act as a distraction. 

Gordon has escaped from prison, and trades Bela a valuable item in exchange for Sam's location. After an encounter with Sam and Dean, Gordon is taken captive by a vengeful vampire who at first plans to feed the famed vampire hunter to his new female companions. Meanwhile Dean tries to gently break the news to Sam that they'll have to kill Gordon when they find him. Sam surprises Dean by agreeing without protest. Later, the boys realize just how badly the vampire's new plan backfired on it when Gordon is turned into what he loathed most. When the boys find out Bela was responsible for Gordon finding them, Dean informs Bela the first thing he's going to do if they survive is kill her, but things appear to be resolved when she helps them locate him. Mercedes McNab guest stars. 

In this Christmas-themed episode, Sam and Dean encounter a twisted couple that insist they are Pagan gods and share a craving for human meat. Flashbacks follow the Winchesters during Christmas 16 years ago when Sam first learned that demons existed and that his father hunted them. 

Sam and Dean run encounter three witches and get a little help from Ruby (Katie Cassidy). 

When Bobby Singer is discovered in a coma, Dean and Sam uncover a demon who works through people's dreams to destroy them. Kripke has revealed in an interview that Jason Voorhees will make an appearance in this episode. [1] 

Agent Henriksen from the FBI descends on small town Monument, Colorado and captures Sam and Dean. He takes over the police station, even letting the one prisoner go, warning the Sheriff that they are the most dangerous criminals he will have ever met. He has his man lead them shackled into the station and the holding cell, leaving them shackled together. When demons attack the police station, killing the Henriksen's partner and several policemen, he blames Sam and Dean, believing they have friends coming to get them out. They try to tell him it's demons and everyone is in danger but he refuses to listen. Ruby finds them and comes up with a solution that no one believes in, forcing them to come up with a better solution.