Season 1 consists of 22 episodes that premiered on September 13, 2005, and concluded on May 4, 2006. The first 16 episodes aired on Tuesdays at 9:00 pm, after which the series was rescheduled to Thursdays at 9:00 pm.
After their mother’s death in a suspicious fire that burns down their house 22 years prior, Sam and Dean Winchester’s father goes missing during a “hunting trip”. As a result, Dean tracks down Sam at Stanford University. The two brothers live a life on the road, in Dean’s black, 1967 Chevrolet Impala with Kansas license plates. However, their father is not a typical hunter: he hunts supernatural creatures like ghosts, vampires, and spirits, and has trained his sons to do the same. Along the way, Sam and Dean save innocent people, fight creatures and ghosts, and collect clues to their father’s whereabouts. Sam begins to mysteriously develop psychic abilities and visions as they travel. They also find another man with abilities similar to Sam’s, whose mother died the same way. They reach out to the young man, Max Miller, offering help and seeking answers. But Max has experienced years of physical abuse and neglect and his life ends in a murder suicide which Dean and Sam are unable to stop. They eventually find and reunite with their father, who reveals that the creature that killed their mother years earlier is the demon Azazel (aka “Yellow Eyes”) and the only thing that can kill him is a legendary gun created by Samuel Colt. It is revealed that Azazel, on a babies six month birthday, would bleed into their mouth and kill the moms when they walk in, this is what gave Sam and Max their powers. The season ends with the brothers and their father involved in a car crash when a truck hits the side of the Impala. They lie inside the car, covered in blood and unconscious.
Season 2 consists of 22 episodes that aired on Thursdays at 9:00 pm beginning September 28, 2006, and ending May 17, 2007.
The season follows Sam and Dean as they deal with their father’s death, who, after the car crash, traded Azazel his life for Dean’s. Sam and Dean continue to hunt Azazel, who caused the fires that led to the deaths of their mother, and later, Sam’s girlfriend, Jessica. They receive assistance from new allies Bobby, Ellen, Jo, and Ash. Part of Azazel’s master plan is eventually revealed as he gathers Sam and others with similar psychic abilities to fight each other, leading to the death of Sam. Dean makes a deal with a crossroads demon to bring Sam back in exchange for his soul, which will be collected in one year and taken to Hell. Azazel opens a portal to Hell, and as hundreds of demons and souls escape, has a final confrontation with the Winchesters. With the help of the spirit of John Winchester, who escaped Hell through the portal, Dean finally kills Azazel and the portal is closed. The Winchester brothers and their allies are left to deal with the demon army that has been unleashed and the one-year contract Dean has before he goes to Hell.
Season 3 consists of 16 episodes that aired on Thursdays at 9:00 pm beginning October 4, 2007, and ending May 15, 2008. Originally 22 episodes were ordered for the third season, but production was halted on December 5, 2007, upon completion of the twelfth episode by the 2007–08 Writers Guild of America strike. The season number was shortened to sixteen episodes, with four new episodes airing in April and May 2008.
The season mainly focuses on trying to save Dean from his deal and tracking down the demons that were released from the gate. Along the way, the brothers meet Ruby, a “good” demon, who has an interest in Sam and claims to be able to help save Dean. Also, they meet Bela Talbot, an acquirer and seller of occult objects, who is constantly a thorn in their side. The brothers eventually learn from Bela which demon holds Dean’s contract: a powerful demon named Lilith. Lilith is the very first demon ever made, with her soul being twisted by Lucifer himself in a spite against god for kicking him out. Lilith takes Bela’s soul after her contract expires, but not before she warns Sam and Dean. The brothers, along with Ruby, track Lilith down and attempt to kill her. Lilith is unable to stop Sam on account of his mysterious abilities; however, Dean’s contract expires and his soul is taken to Hell.
Season 4 consists of 22 episodes that aired on Thursdays at 9:00 pm beginning September 18, 2008, and ending May 14, 2009.
Dean is rescued from Hell and brought back by an angel of the Lord named Castiel, one of several angels who appears throughout the season. The rest of the season follows the brothers as they work with Castiel to stop Lilith’s plan of breaking the 66 seals, which would allow the fallen archangel Lucifer, AKA “the Devil” or “Satan himself”, to walk the Earth free once again. The relationship between Sam and Dean is strained. Sam starts siding with Ruby over Dean. He begins to give into his demonic side by drinking demon blood to become strong enough to defeat Lilith. He and Dean eventually have a falling out. Sam sides fully with Ruby in his obsessive quest to kill Lilith. Dean makes a deal with the angels to save Sam, and learns that the angels want the Apocalypse to occur in order to rebuild Paradise on Earth. With aid from Castiel, Dean escapes and tries to stop Sam after learning that Lilith is, in fact, the last seal, but Sam kills her anyway, breaking open Lucifer’s prison. Ruby reveals her true colors as a demon loyal to Lucifer and Dean kills her. As the season ends, Lucifer’s cage opens and he escapes from Hell.
Season 5 consists of 22 episodes that aired on Thursdays at 9:00 pm beginning September 10, 2009, and ending May 13, 2010. This season was rumored to be the last season, because Eric Kripke had said previously that he planned the show to run for only five seasons. Despite this, Padalecki and Ackles had contracts for a sixth season, and The CW renewed it for season six on February 16, 2010.
The fifth season revolves around the fight to stop Lucifer and save the world from the Apocalypse, inspired by events in the Book of Revelation. Throughout the season, while Castiel searches for God, Sam and Dean battle both angels and demons as they fight their destiny to become the vessels of Lucifer (Sam) and Michael (Dean), respectively. One way they attempt to stop Lucifer is to retrieve the Colt from the demon Crowley and kill Lucifer with it, but this fails as Lucifer can’t be killed by the Colt, and they lose fellow hunters and friends Jo and Ellen in the process. Their loss, and the revelation that God will not help stop the Apocalypse, drives Dean to agree to act as the vessel of Michael, but, ultimately, he doesn’t go through with it. Instead, Dean kills the angel Zachariah, who has been tormenting the brothers all season. Michael ultimately takes Adam Milligan, the newly resurrected half-brother of Sam and Dean, as a vessel instead. Unable to defeat Lucifer, Sam and Dean, with information from the Trickster, revealed to be the archangel Gabriel, and with help from the demon Crowley, decided to collect the rings of the Four Horsemen of the Apocalypse, including Death, which act as the key to Lucifer’s prison. The concept of destiny versus freedom, choice, and free will plays a large role. Throughout the season, Dean, Sam, Castiel, and Bobby each have a crisis as they near giving up. However, through each other’s support, they continue forward until the end. It is also notable that Dean and Castiel have an ongoing friendship during this season, while Dean and Sam initially grow further apart. In the end, Sam allows Lucifer to possess him and he kills Bobby and Castiel, who is now human. Sam then manages to regain control, thanks to his bond with Dean, and throws himself (while possessed by Lucifer) and Adam (possessed by Michael) into the Cage to trap Lucifer once more. Castiel is resurrected by God and, more powerful than ever, resurrects Bobby and then returns to Heaven to restore order. Dean returns to his old girlfriend Lisa to live a normal life. Sam is next shown mysteriously free of the Cage, watching his brother eating dinner in the house with Lisa and her son Ben.
Season 6 consists of 22 episodes that aired on Fridays at 9:00 pm beginning September 24, 2010, and ending May 20, 2011. Beginning with this season, Kripke did not return as showrunner, but still remained as a hands-on executive producer, leaving executive producer Sera Gamble to take over the reins.
The sixth season begins a year after the conclusion of the fifth season, with Dean living a somewhat happy life with Lisa and Ben. When an emotionless Sam returns to Dean, he is forced to leave his new life behind and work with his resurrected grandfather Samuel to capture Alpha monsters for the Crowley. The brothers are unable to get much help from Castiel since his time is occupied by a civil war raging in heaven against the archangel Raphael. Dean does not trust Samuel and his suspicions are confirmed when he finds Samuel working with demons to discover the location of Purgatory. Dean discovers that Sam’s soul is still in the Cage, so he implores the Horseman Death to retrieve it. To ensure Sam does not remember his time in the Cage, as it may be too much for him to handle, Death blocks that part of Sam’s memory using a mental wall. The season’s second half revolves around the so-called Mother of All, which ultimately leads to events which prove that Castiel is behind the circumstances of Sam’s return, the hunt for the Alpha monsters, and the search for Purgatory and was working with Crowley the entire time. When the brothers try to stop Castiel, he brings Sam’s memory of the Cage back and proceeds with his plan, absorbing all the souls from Purgatory and pronouncing himself God, having ascended beyond a mere angel.
Season 7 consists of 23 episodes that aired on Fridays at 9:00 pm beginning September 23, 2011, and ending May 18, 2012.
After absorbing all the souls from Purgatory and declaring himself God, Castiel goes forth to punish all the wrongdoers in the world. Very quickly, though, he discovers that he absorbed the Leviathans, who are attempting to break free of his vessel. Sam and Dean manage to return most of the souls to Purgatory but fail to return the Leviathans, who seemingly kill Castiel before vanishing. The Leviathans inhabit the bodies of many different people around the world. Sam and Dean learn that their weakness is Sodium Borate (aka Borax), though it has minimum effectiveness on the Leviathan leader Dick Roman. After Roman kills Bobby, Dean becomes obsessed with taking the Leviathans down and learns of a facility they are building, only to discover that it is a facility to cure cancer. As one Leviathan states, “We’re only here to help”. The spirit of Bobby later confirms that while they are curing disease, they are doing it as part of their grand plan to turn humanity into the perfect food source. With the help of Castiel, and Kevin, a prophet of the lord, the brothers learn that the only way to kill the Leviathans is with the “bone of a righteous mortal washed in the three bloods of the fallen” and set out to find the three bloods. Kevin can read the word of God and helps Sam and Dean decipher the word to stop the Leviathans. Eventually, Dean and Castiel kill Dick but are dragged into Purgatory as a result, while Sam is left alone to deal with Crowley, who plans to rise to power now that the Leviathans are disorganized.
Key plot points presented in the season were Sam struggling with the constant hallucinations of Lucifer and the ghost of Bobby “haunting” Sam and Dean through his alcohol flask. Bobby’s rage toward Dick Roman slowly causes him to become a vengeful spirit, and Sam and Dean ultimately deal with this by burning the flask at his request, thus destroying Bobby.
Season 8 consists of 23 episodes that aired on Wednesdays at 9:00 pm beginning October 3, 2012, and ending May 15, 2013.
One year after being dragged to Purgatory, Dean returns to Earth without Castiel, carrying inside his body the soul of a vampire named Benny. The two brothers begin a fight against Crowley to find the Demon Tablet and lock the Gates of Hell, thereby trapping all demons in Hell. All the while fighting Metatron, the scribe of God, who they think is on their side but is really trying to become the new God himself. The brothers use Kevin Tran to help them read the tablet and accomplish their goal. Castiel is brought back by an angel named Naomi and takes possession of the Angel Tablet. After realizing that to lock the Gates of Hell Sam must die, Dean ends the trials. Castiel, however, is stripped of his grace by an angel named Metatron who proceeds to have millions of angels locked out of Heaven. The season ends with millions of angels falling to the sky.
Season 9 consists of 23 episodes that aired on Tuesdays at 9:00 pm beginning October 8, 2013, and ending May 20, 2014.
In the first half of the ninth season, the angels have fallen to Earth and two factions are warring against each other while hunting Castiel, rogue angels roam the Earth causing trouble as well. Castiel is now human and having to adjust to his new life while Crowley is held prisoner by Sam and Dean who are trying to use an old ritual to turn Crowley into a human again, and not a demon. All the while Abaddon works to take over Hell. Sam is left near-death from the Trials of God and Dean is forced to let an angel claiming to be Ezekiel possess Sam to heal him from the inside. While dealing with the various threats that crop up, Dean must hide Ezekiel’s presence from Sam so he won’t expel him and die while also keeping Castiel away at Ezekiel’s demand. The brothers must also search for a way to return the angels to Heaven. Eventually it is revealed that Ezekiel is actually the angel Gadreel who let Lucifer into the Garden of Eden. Gadreel murders Kevin Tran and escapes while Castiel regains his powers. With Crowley’s help, Sam expels Gadreel, but the experience causes Sam and Dean to split up while letting Crowley go as part of the deal Dean made for him to save Sam.
In the second half, Dean begins searching for both Gadreel for revenge and the First Blade to kill Abaddon with the help of Crowley with whom he forms a reluctant alliance as Abaddon has begun attempting to take over Hell and is “much worse” than Crowley. Despite being warned of terrible repercussions, Dean takes on the Mark of Cain in order to be able to wield the First Blade. After healing Sam completely, Castiel begins a search of his own for Metatron, believing him to be the key to reversing the expulsion of the angels. Metatron begins trying to unite all the angels under his rule while Castiel leads other angels against him to retake Heaven. Eventually Dean kills Abaddon and Castiel defeats Metatron with the help of a repentant Gadreel, but Metatron kills Dean, causing him to become a demon himself due to the influence of the Mark of Cain.
In Season 10, after being resurrected by the Mark of Cain, Dean is now a demon, working alongside Crowley. Meanwhile, Sam continues to search for Dean. After Dean refuses to follow Crowley’s order and embarrasses him in front of his demon followers, Crowley gives Sam his brother’s location. For giving up Dean, Sam gives Crowley the First Blade. Later, Sam, with the help of Castiel, cures Dean by using sanctified human blood and returns him to his human state. After being cured, Dean is reminded by Castiel that the Mark of Cain is still a problem. Dean and Sam help Castiel track down Claire, Castiel’s vessel and Jimmy’s daughter. Dean ends up slaughtering several men who are keeping her captive and loses control of the Mark, a nightmare he previously had.
Meanwhile, a mysterious new witch comes into play, being revealed to be Crowley’s mother, Rowena. Also, the angel Hannah goes back to Heaven so that her vessel can have her life back. A large focus of the season is Dean’s quest to overcome the Mark of Cain and have it removed if possible. After the Mark causes him to break Charlie’s arm, Sam suggests that Dean has the ability to at least partially control the Mark, but only if he can control himself. New hope for ridding Dean of the Mark comes when Charlie unearths the Book of the Damned. Sam needs help in reading and using this powerful tome, and turns to Rowena for help, keeping the entire thing a secret from Dean. He requests help from Charlie, too, who decodes the text but is murdered by the Steins, a family that has secretly controlled much of history. After massacring the Steins, nearly killing Castiel and getting another hunter killed, Dean starts despairing of being free of the Mark, causing him to turn to Death for help. Death proposes putting Dean in isolation away the Earth, but insists Dean must kill Sam, who otherwise would work to bring Dean back. Sam and Dean both agree that it is for the good of the world. At the last moment however, Dean seemingly kills Death instead to save Sam. Oblivious to the dangers, Rowena successfully casts the spell to remove the Mark and unleashes the Darkness, a primordial evil that had been kept away by the Mark. Rowena also places Castiel under a spell so he attacks Crowley as she escapes with the Book of the Damned.
Season 11 premiered on October 7, 2015, and consists of 23 episodes that aired on Wednesdays at 9:00 pm.
In this season, Sam and Dean deal with the release of Amara/The Darkness, after Rowena’s spell removed the Mark of Cain from Dean’s arm. Soon, they find out that Dean and Amara are, somehow, bonded. Meanwhile, a mysterious black fog is killing people in a nearby town. When Dean and Sam attempt to save those people, they meet Deputy Jenna Nickerson, who’s taking care of a newborn baby girl whose father was infected and eventually died. The baby is taken to Jenna’s grandmother’s house, where the baby begins levitating toys. This prompts the old lady to call an exorcist, and Jenna to call Dean. When Dean arrives, he finds out the exorcist is Crowley, who found out the baby is The Darkness, and eventually flees taking her with him. Meanwhile, Sam begins to have visions, that he claims to be sent by God.
While Crowley’s taking care of Amara, feeding her with souls, the brothers are, alongside Castiel, trying to find a way to kill The Darkness. In order to find out more about Amara, Castiel asks Metatron for help, and he says that in order to create the world, God had to sacrifice His sister, The Darkness. At this point, Sam is having visions from the cage, where Michael and Lucifer are trapped.
To face the most dangerous creature they’ve crossed paths with so far, the brothers, alongside Crowley, Castiel and Rowena, go to hell in order to ask for Lucifer’s help. Lucifer claims he’s the only one that can beat Amara, but in order to do so, he needs to possess Sam’s body. Also he tells Sam that the release of The Darkness weakened The Cage and he’s been the one sending Sam’s visions and that God was never helping them. When Sam refuses, Lucifer tries to kill Dean, Sam, and Castiel, but Rowena’s spell seems to have sent him away. Later, it’s revealed that Castiel said “yes” at the last second, and that Lucifer is now possessing his body. Then, Lucifer takes control of Hell and kills Rowena.
After a while of being fooled by Lucifer, the brothers find out that Castiel is no longer among them, and that it was Lucifer who was in control. Meanwhile, they’re seeking the Hand of God, a couple of artifacts that were touched by God Himself, and that can unleash a great amount of power, and it’s believed to be able to kill the Darkness.
When nothing works, Amara claims that God must appear Himself to see her destroying everything He created and loves. Then, she decides to draw out God by torturing an archangel, making Lucifer/Castiel scream in agony. Meanwhile, Chuck returns and reveals himself to Metatron, telling him He is God. Then, He reveals Himself to The Winchesters and they all decide to seal Amara. Rowena, who had cast a spell that made her immortal, helps them with a spell, while Crowley and Lucifer use the demons and the angels to make a combined attack against Amara. When Chuck tried to seal Amara, she resisted, stopping the Winchesters, apparently killing Lucifer and gravely wounding Chuck. Amara warns that Chuck is not dead yet because he is going to watch her destroy everything ever created.
After finding out that Lucifer’s gone and that Castiel is back, they find a fatally injured Chuck. As a result of Chuck’s injuries, the sun is now dying and the world along with it. Realizing that the only chance for the world to survive is to kill the Darkness along with Chuck, the Winchesters begin gathering ghosts to create a bomb to destroy the Darkness. With the help of Billie the Reaper, they are able to get the needed souls which are inserted into Dean. Chuck sends Dean to Amara who has started to regret her actions and Dean convinces Amara that revenge is not worth it. Amara and Chuck reconcile and Amara heals Chuck of the damage she did to him. The two then leave the Earth, but not before Amara tells Dean she is going to give him what he wants most for helping her. At the bunker, Castiel is banished by a woman who identifies herself as Lady Antonia Bevell of the London chapter of the Men of Letters. Antonia tells Sam the Men of Letters have sent her to bring Sam in for punishment for his actions and fires her gun, apparently at Sam as he tries to talk her down. Making his way through the woods, Dean finds his resurrected mother.