|“||I always wondered, ever since I took that burden, that curse, I wondered what it could be what -- what my true happiness could even look like. I never found an answer. Because the one thing I want... it's something I know I can't have. But I think I know -- I think I know now. Happiness isn't in the having. It's in just being. It's in just saying it. (...) I know. I know how you see yourself, Dean. You see yourself the same way our enemies see you. You're destructive and you're angry and you're broken. You're -- You're "Daddy's Blunt Instrument." And you think that hate and anger that's -- that's what drives you. That's who you are. It's not. And everyone who knows you sees it. Everything you have ever done, the good and the bad you have done for love. You raised your little brother for love. You fought for this whole world for love. That is who you are. You're the most caring man on Earth. You are the most selfless, loving human being I will ever know. You know, ever since we met, ever since I pulled you out of Hell, knowing you has changed me. Because you cared, I cared. I cared about you. I cared about Sam. I cared about Jack. I cared about the whole world because of you. You changed me, Dean. (...) Because it is. I love you. (...) Goodbye, Dean.||”|
— Castiel's last words to Dean
Castiel, often shortened to Cass, is a powerful angel of the Lord who was responsible for saving Dean Winchester from Hell, on the archangels' command. It was his job to help prevent Lilith from breaking the 66 Seals that, once broken, would release Lucifer from his cage in Hell. Once Castiel learned that the angels wished to free Lucifer anyway, he defied his angelic brethren and died trying to help Dean prevent Sam Winchester from breaking the last seal.
After he was killed by the Archangel Raphael, Castiel was resurrected by God and joined Sam, Dean, and Bobby Singer in a quest to prevent the brothers from becoming the vessels of Michael and Lucifer. Castiel would later be killed by Lucifer but his actions allowed Sam to trap both Archangels away. With the Apocalypse averted, Castiel was again resurrected by God with new powers, being promoted to Seraph. He then started a civil war in Heaven to prevent Raphael from restarting the Apocalypse, Believing he could not be outsmarted by a demon, Castiel teamed up with Crowley to claim the souls of Purgatory. He ended up betraying Crowley and absorbing all the souls, resulting in his powers reaching a level much higher than that of an archangel, but at a high price: the powers that the evil souls granted him had went to Castiel's head, causing him to proclaim himself as the new God.
As his body started to rot, Castiel later agreed on the advice of Dean to release the souls back into Purgatory. While seemingly successful, it turned out that the one of the most powerful entities from Purgatory, the Leviathans, held on to Castiel, and overpowered and took control of him. When the Leviathans left to take over new forms, Castiel was presumed dead, but survived – apparently resurrected by God yet again. Dean later accidentally finds Castiel as an amnesiac healer called Emmanuel. After taking on Sam's madness and experience in Hell in order to save the Winchesters and redeem himself for what he did to Sam, Castiel had become insane and fell into a coma. However, he awakens and his sanity is returned to an extent when a signal was sent to all angels upon the discovery of the Word of God and the appointment of a new prophet. He then aids the Winchester brothers against Dick Roman, only to be transported to Purgatory with Dean.
While Dean comes back, Castiel has not returned with him. While his condition is initially unknown, it's revealed that he spent most of his time running from Leviathans and that he didn't escape Purgatory with Dean as he had planned to stay as a form of penance. However, he was eventually released from the monster realm by an incursion of angels under the orders of a mysterious but powerful angel named Naomi, rejoining the Winchester brothers and trying to become a hunter himself. But after a long while, Castiel learned that Naomi had been controlling him ever since she got him out of Purgatory and compelling him to find the angel tablet, at any cost, even going as far as killing Dean. After he almost did so, Castiel then teamed up with Metatron when the angel convinced him to help him close the gates of Heaven. So after collecting the heart of a nephilim and the bow of cupid, Metatron is eventually captured by Naomi but escapes and kills her, only for Cass to discover Metatron's betrayal and plan to cause all angels in Heaven, even the imprisoned ones, to fall to Earth.
After being stripped of his grace by Metatron in order to expel all angels from Heaven, Castiel spends the next three months on Earth as a human. After being captured and tortured by an angel named Malachi, Castiel steals the grace of Theo and returns to his original status as an angel (previously being promoted to a Seraph). Castiel later assists Dean with expelling the angel Gadreel from Sam and heals Sam's wounds. After Dean leaves with Crowley to find a way to defeat Abaddon, Castiel also leaves to begin a search for Metatron and Gadreel while being pursued by other angels, and eventually killing rebel leader Bartholomew, he assumes command of his faction. However, a deception of Metatron's makes him lose his army; instead he teams up with angels Gadreel and Hannah to infiltrate Heaven and destroy the angel tablet, cutting off Metatron's power to allow Dean to kill him. Though successful, Dean and Gadreel are killed, while Castiel locks Metatron up. He then left Heaven as he didn't want to be a leader and was dying due to his burning-out grace before Crowley saved him with Adina's grace. He has since reclaimed the last of his own grace and restored to full power and being a Seraph once again.
After the release of the Darkness and the trauma he suffered under Rowena MacLeod's spell, Castiel agreed to act as the vessel for Lucifer to walk the Earth once more so Lucifer could battle the Darkness. Castiel would remain Lucifer's vessel for months, only emerging briefly to save Sam's life and convince the angels to help against the Darkness. At the end of the conflict with the Darkness, Lucifer was exorcised from Castiel by the ancient being, leaving Castiel in control of himself once more. During this time, he finally found God, who returned to defeat the Darkness as well.
After Lucifer was exorcised from him, Castiel would dedicate himself to finding the fallen archangel and locking him away, blaming himself for Lucifer being free upon the Earth once more. This task caused Castiel to reluctantly work closely with Crowley, who also desired Lucifer gone. Following Lucifer's apparent defeat, Castiel dedicated himself to hunting down Lucifer's son Jack, a dangerous Nephilim. After a battle with Dagon that resulted in Castiel's brief empowerment by the Nephilim fetus, Castiel became convinced of the child's supposed goodness and chose to become his protector and guide, forsaking the Winchesters in the process. While trying to lock Lucifer in an alternate reality, Castiel was killed once more by the Fallen archangel.
Following his death, Castiel was then sent to The Empty, where all angels and demons go when they die, to sleep for eternity. He was awoken from his eternal slumber when Lucifer's son Jack called his name. He was soon expelled from The Empty by the realm's guardian, The Shadow, for interfering with the latter's slumber, refusing to sleep again, and demanding his release, allowing him to be resurrected as a result. Castiel soon reunited with the Winchesters and Jack to help them out in their hunter cases. He later met with Lucifer who returned from the other world and warned him about the invading Alternate Michael. While in debate over recruiting Jack, Castiel and Lucifer were captured by Asmodeus, with Castiel being used as bargaining chip for the Winchesters. Castiel escaped and was betrayed by Lucifer who nearly killed him but he retaliated before the latter fled and Castiel returned to Sam and Dean to warn them about the impending threat. Castiel was also reunited with his brother Gabriel who wanted no part in the conflict as Castiel set out to locate him to get him to help in restoring Heaven. Very soon, Gabriel joins the team and after they capture Lucifer. They later travel to the Apocalypse World, and find Jack and Mary. The group is also aided by Lucifer after he escaped and decided to help out. Castiel evacuated with the others back to Earth but at the cost of Gabriel. They faced a new problem as Michael made his way there and Castiel finally met his enemy who tossed them aside. Jack wounds Michael, but then has his grace stolen by Lucifer. So Dean agrees to be Michael's vessel and kills Lucifer, at the cost of losing control of his body.
At the beginning of season 14, Castiel is committed to finding Dean, who was possessed by Michael and disappeared after defeating Lucifer. He resorts to a demon, Kipling, who lures him into an ambush and uses Castiel as a bargaining chip to meet Sam and get his support to become King of Hell. Together, however, Sam and Castiel defeat Kipling and his henchmen. Dean is found, in full possession of his conscience and with no sign of Michael. Jack, however, begins to decline in health, having lost his grace earlier, and then dies. The Winchesters seek Lily Sunder to help resurrect Jack, and Castiel goes to heaven to find his spirit and bring him back to his body. Heaven, then, falls under attack from the Shadow, who wants to take Jack to the Empty. In order to stop him, however, Castiel convinces the Shadow to take him in exchange for Jack; the Shadow agrees, but says that he will not take Castiel's life until much later, when the angel will have forgotten their conversation and experienced a moment of happiness. Jack is resurrected and, with the help of Sunder's magic, he defeats Michael and consumes his grace, thus regaining his powers; during the battle, however, he had to burn out what was left of his human spirit, getting in a state similar to that of soulless humans, amoral and without emotions. In that state, he kills Mary Winchester, causing Dean to turn against Castiel, as the angel had hidden from him what'd happened to Jack. In the end, Chuck reappears and tries to manipulate the Winchesters and Castiel to kill Jack in a showdown at a cemetery, but the trio refuses, causing Chuck to personally smite Jack and Team Free Will to then attack him. Furious, Chuck opens up all closed doors of hell and lifts undead corpses from their resting ground, thereby causing the second apocalypse.
The Winchesters and Castiel try to stand their ground against the zombies awakened by Chuck. They receive unexpected help from Belphegor, a heretofore unknown demon who, to Castiel's chagrin, is possessing Jack's dead body. To stop the ghosts from leaving the tear that Chuck opened on the surface of Earth, which leads to hell, and neutralize those who already made their departure, Rowena joins the group to perform a Book of the Damned spell, while Castiel and Belphegor descend to hell in search for Lilith's Crook, an instrument manufactured by the white-eyed demon that can suck in demons and ghosts who try to escape hell in disobedience. Castiel, who is suspicious of the demon, initially refuses to escort him back to hell, but is forced to do so by Dean, who still resents the angel and doesn't want him around. Castiel discovers Belphegor wanted his company so that he could read the Enochian incantation that can open the Crook's box, and that his plan all along was to use the object to absorb the spirits of hell into himself, become more powerful, and take over hell's throne. Castiel throws himself at Belphegor while he plays the instrument, smiting him so badly that Jack's corpse is burned to a crisp and the Crook is destroyed. Castiel manages to return to the surface of the Earth, and he tells Dean he couldn't let Belphegor fulfill the plan to suck in all of hell's souls, enraging Dean - against his friend. Since the Crook is gone, Rowena decides to cast a spell so that she can herself absorb the spirits inside her own body, dying in the process. The death of their witch ally further intensifies Dean's anger at Castiel, and in an argument at the bunker he throws in the angel's face that everything that goes wrong in the group's endeavors has been Castiel's fault. Tired of weathering the storm of his friend's moods, Castiel says that he is dead in Dean's eyes and so it is best that he move on without the Winchesters. Later, he ignores Sam, who tries to contact him via phone messages. Castiel subsequently returned to the brothers to help them defeat God by grooming a resurrected Jack to become stronger. After the plan fails and they are chased by Billie, Castiel sacrifices him by confessing his love for his close friend and allows himself to be happy. This activates his deal with the Shadow who drags him and Billie into the Empty.
Castiel's legacy has seemed to have become legendary among angels and demons alike, as many recognize him as the only angel who defied God's rules and cooperated with humans due to his own decision, which he is either loathed or respected for. He is also the only angel to have been killed, and been resurrected multiple times. He is the only known angel who has repeatedly been resurrected by God so he could help Sam and Dean Winchester.
As an angel, experiencing Castiel's true form will result in blindness, deafness, or even death, as the appearance of his natural visage is so overwhelming that it is capable of burning human or demon eyes from their sockets (as seen in Lazarus Rising), as he said to Dean, "My true form. It can be overwhelming to humans and so can my real voice." However, Castiel stated certain, "special people" are able to tolerate his true appearance and voice. Although his true form has never been seen, it is known that he has two feathered wings. When Castiel becomes a seraph, he describes himself to Samuel Campbell as a "multidimensional wavelength of celestial intent" and his true form is "approximately the size of your Chrysler Building" in height. As he was promoted to a seraph, it stands to reason his true form has changed to one of a seraph's. It is presumed to be very tremendous and terrifying, as the mere image of it was enough to cause Crowley to flee in fear of being smited. In addition, Castiel has been referred to as being attractive on more than one occasion, both in his human vessel and his true angelic form. One female demon, while talking with Crowley, once instantly said Castiel was, as she said in her words, hot, as she also said, "I mean, human Castiel? eh. But, feathered Castiel? Phew." The same demon even once called him "Captain Sexy." Another instance was a woman who referred to him as "young and sexy" while he was god and had recently killed a pastor at the church she attended. Since having his grace removed for Metatron's spell, Castiel has lost his wings, even with Theo and Adina's grace. Though he has since regained the remnants of his grace and been restored to full power, his wings are broken.
For humans, they see him as the appearance of his vessel, Jimmy Novak, who is a handsome man of average height in his thirties. He sports a pair of dress shoes, a black suit, a buttoned white-striped dress shirt, and loosened blue necktie accentuated by a beige trench coat. Although he has a very dire demeanor, his outward appearance radiates a natural calm and serenity which makes conversation easy and direct. Since his third resurrection, his appearance has changed. He lost his trench coat upon his third death and when he became amnesic, he wore different clothes. Upon regaining his memories, Dean gave him back his trench coat, but he still wore Emmanuel's clothes until he became insane. While insane he wore his trench coat and hospital scrubs. While in Purgatory he retained the same outfit, albeit extremely dirty and torn off. Castiel also grew a beard and his hair became messier. After returning from the monster realm, Castiel returned to his original appearance. He kept this until he lost his grace and became human. While he initially kept his usual clothes, they became dirty and he was unable to clean them and get food and water so he abandoned the trench coat and suit and took to wearing more casual human clothes, though he did wear a suit when he pretended to be an FBI agent. After becoming an angel again, Castiel donned a new suit and trench coat, albeit not as accented as his previous trench, nor as long. He at first didn't wear a tie like before, but after a suggestion from Claire Novak that he looked better in a tie, Castiel donned the blue striped tie from his FBI suit and continued to wear it in the next seasons.
As of Season 13, Castiel returns to his classic attire of seasons 4-8 with a new black suit, and trench coat. His tie is once again a single shade of blue.
In 1901, Castiel possessed a female vessel and dressed as a woman from that era. Notably, he wore a coat very similar to the trench coat he wore in his first appearance. It is safe to say that, like most angels, Castiel does prefer to retain his vessel's original appearance and clothing. He does not seem to have a high fashion sense, preferring neatness over beauty.
Castiel is a strong, determined, impulsive, competitive and naïve celestial being. Like most angels, Castiel expresses little to no emotion, which creates flaws and complexities in his persona. Despite this, he does not display the blank apathy or mocking superiority that seem to characterize angels such as Uriel or Lucifer. His lack of emotion and understanding of human behavior such as sarcasm has led to several humorous situations throughout the show, and has occasionally gotten him into trouble with humans, ultimately leaving Dean or Sam to amend the situation. He does, however, become close friends with the brothers, who encourage him to be kinder, more caring and more selfless.
Unlike some of his brethren, Castiel still has faith in God, though not to the zealot-like extent displayed by Michael. While he admits he may not always understand what God wants and may question his reasoning, Castiel always follows his father to the best of his abilities. This, along with his interest in humans, has caused other angels to label him as weak or naïve, but also peculiar. Anna Milton and Lucifer have both displayed this attitude, with Anna calling him a hypocrite for refusing to rebel in order to gain more freedom. Castiel briefly loses this faith after Joshua reveals that God doesn't care and falls into a depression for some time. However, when God resurrects him for a second time, his faith returns. Castiel frequently exhibits what could be referred to as affection towards Dean, and seems to express regret, hesitance, and anger at several points.
Being around the Winchesters, paired with his experiences in the War, have taught Castiel several "tricks" that have helped him during the show. While not possessing free will in the same sense as a human, Castiel has learned how to bend the rules at times, like in season 4. The best example is when he informs Dean about Chuck's archangel, thereby giving Dean the idea to use him to save Sam from Lilith (The Monster at the End of This Book). He was also able to distract Meg long enough to use her. This was similar to a trick Uriel performed to free Alastair, Castiel used Meg for his trick to free himself, from a ring of holy fire (Abandon All Hope). It is also possible he learned from the demon Crowley to wipe out loyalists of his adversary, Raphael. Castiel also considers himself to be the Winchester's personal guardian angel.
When Castiel is brought back from the dead after Lucifer kills him, his personality begins to shift. During Season 6, Castiel becomes more prideful. It is because of this pride that Castiel makes a deal with Crowley, and starts the civil war in heaven. During this time Castiel showed extremely high ambition, doing everything he could to open the door of Purgatory. He also displayed his intelligence, being capable of tricking Dean, Sam, Raphael, and even Crowley (well known as a crafty trickster.)
Upon absorbing the souls, Castiel's hubris grew to the extent that he claimed to be the new God. It was later revealed that others, such as Death, thought of him only as a mutated angel. Previously acting kind, assuring, and fierce at times, Castiel had now become almost purely cold and absolute in his decisions. This is displayed when he kills Raphael without any second thoughts. Mere seconds later, he demanded that Dean, Bobby, and Sam kneel before him and be by his side. Castiel claimed he would destroy them if they forgot their place and rose up against him. However, he still had some lingering affection for them, trusting them enough to leave them alone. They soon realized that he was out of control and that being influenced by the Leviathans. Later, when Castiel returns to his original personality, he feels incredibly guilty and goes back to his friends for help. Knowing Dean is furious with him for breaking Sam's wall, Castiel expresses true remorse for his actions and swears to do all he can to make up for what he did.
After his third resurrection, Castiel lost his memories and took on a more human personality, though he was still more distant than normal humans. He expressed affection for his wife Daphne Allen, and retained his desire to help people as shown by the fact that when he rediscovered his healing powers, he used them to heal people in need, also showing great compassion. While shocked by the existence of demons, he took it relatively well once it was explained to him. He was perceptive enough to realize that Dean couldn't forgive "Cass" for what he had done and felt betrayed and that he himself was the Cass mentioned after overhearing some of Dean's conversation with Meg. In his human mindset, he had no idea of what he was capable of and was nervous with the idea of using his powers to kill demons when he had no idea how. However, despite this, he displayed courage in agreeing to try and seemed to still possess an instinctual knowledge of how to use them as he quickly figured out what to do.
After recovering his memories, Castiel's normal personality more or less returned, and he was overcome with guilt over what he had done, how many he had killed, and for releasing the Leviathans, even questioning why he was still alive. Following his awakening, his personality was greatly modified, due to a combination of what he had taken from Sam and his own guilt. It made him inattentive, overly calm, uncaring and seemingly dim. He also became a pacifist, and refused to fight, even when being attacked, as well as being overly optimistic, perceiving many negative things in a positive way. During this time he developed a unique relationship with Meg, a demon, as she was his caretaker during his insanity. He showed open attraction to her, calling her a "thorny beauty". Although Meg doesn't return the feelings at the start, a year later she openly flirts with Castiel, and Castiel seemingly returns the attraction. In Survival of the Fittest, Castiel explains that his pacifism comes from being afraid of causing more damage with his actions. However, he agrees to break his pacifism and help stop the Leviathans, possibly out of loyalty to Dean as he agrees after Dean says he'll likely die trying to stop them. After agreeing, he doesn't hesitate to fight, helping to dispatch Royce and getting in front of Dean to protect him from Dick Roman and later restraining the Leviathan leader so Dean can kill him. Castiel also displays a bleak view on his resurrections: instead of believing it to be a gift from God for his service, he now sees his resurrections as punishment for his actions, telling Dean "I see now it's a punishment resurrection, it gets worse every time."
After he and Dean were sent to Purgatory, his sanity and original personality was restored, although he himself states nobody could ever be sure if he is indeed sane. Following his return in A Little Slice of Kevin, Castiel displayed a slightly more laid-back personality and a much less detached persona and showed human emotions as well as a taste for human things, as he commented how he missed watching TV. He has also developed a strong desire for penitence, looking for anyway possible to redeem himself for the devastation he caused Heaven and his fellow angels.
Since becoming human briefly, Castiel has become more human. He expresses more of an appreciation for human things and develops more human emotions such as romantic attraction. He also became less serious, drinking a beer with Sam and Dean and joking around. He proved to be good enough at being human that he was able to fool law enforcement and pose as an FBI agent, something he could never do successfully before even with coaching from Dean. Even after becoming an angel again, Castiel hasn't seemed to lose his human emotions, getting very angry when he realized who Gadreel was and freely expressing it and comforting a distraught Dean, understanding why he was so upset rather than being confused as he would have been in the past. While briefly human, he was ready to embrace his new status, excited to have Sam and Dean as his teachers and seemed to see his return to being an angel as a necessary evil more than something he wanted and called his stealing of the grace of Theo as barbaric and something that made him as bad as the other angels. Castiel also seems to now understand human ways better, able to drive and steal a car, a skill he never previously showed, though he still lacks full knowledge of everything as he didn't know to get gas. He also developed a taste for human food, something that was made harder by the return of his angel powers and completely lost any former disgust he had towards Sam, finally understanding why he'd done everything he did. Castiel also learned that the ends don't justify the means when it means sacrificing lives. Thanks to Metatron, Castiel has also finally gained the ability to understand Dean's constant movie and TV show references, something that had previously frustrated him into always saying "I don't understand that reference." This helps him now understand human culture better.
Castiel seems to have a fondness for his usual appearance as he never changed until he briefly believed he was human. At first he may not have changed out of lack of necessity, but after returning from Purgatory, he put back on his usual outfit and was very pleased to be able to do so. He seemed to be particularly fond of his trenchcoat as even insane he wore it and was seen to only reluctantly let it go when as a human he was unable to afford to cleaning it. After becoming an angel again, he donned a new trenchcoat and suit, once again displaying his fondness for that particular attire.
In the aftermath of being put under the Attack Dog Spell by the witch Rowena, it, according to Metatron, made Castiel broken and paralyzed due to the trauma and due to him attacking other people, including Dean. Even after Castiel was free from the spell, it still has also apparently "scarred" Castiel so deep that Cass wouldn't even leave the bunker. Even Metatron, who is now human, noticed it especially when he said Castiel couldn't even hit him. However, while he misjudged it as Castiel being afraid, after being hit and thrown by Castiel multiple times, Metatron then realized that Cass is not scared, but is actually angry instead about, as Metatron said, "being everyone's tool. Manipulated and used by the angels, by your enemies, by your friends." Even Castiel himself said that he is tired of having his strings pulled.
Castiel eventually allowed Lucifer to possess him in order to be useful to the fight with Amara, seeming to see himself as useless now. Castiel only fought Lucifer once to protect Sam, but was unable and unwilling to expel Lucifer from his body. When Crowley entered Castiel to get him to expel Lucifer, Castiel was shown to have become apathetic to the whole situation and intended to just wait the fight out, not intervening even when Crowley and Lucifer fought it out in his mind and simply scolding them for bothering him. Crowley believed that Lucifer did something to Castiel to cause this, that Lucifer "got his hooks in good." When given control by Lucifer to speak to the angels, Castiel displayed his regular personality rather than the one Crowley saw in his mind and stated that he truly believed his role in the upcoming fight was to give Lucifer form on Earth so he could aid God in defeating the Darkness. After Lucifer is expelled from Castiel by Amara, Castiel seems to return to his old self completely with the archangel's influence gone from his mind, but continues to believe he did the right thing by consenting to Lucifer's possession.
Now free from an impending war, Castiel seeks to capture Lucifer for he believes himself to be responsible for letting the archangel out, going so far as to decline help from Sam and Dean but accepting Crowley's simply because the demon proves useful, though Castiel repeatedly expresses dislike in having to work with Crowley, calling the situation "unfortunate". Unusual for his character, Castiel has begun using sarcasm and now throws around witty retorts, most notably at Dean. However, it should be noted that Castiel continues to feel out of place and in a desperate need to prove himself.
As noted by Uriel, Naomi, Metatron and Ishim, Castiel is very attached to his ward, Dean Winchester, though he has come to include Sam and Mary as people in his care, and despite accusations that these three humans make him weak, Castiel defends that they are the source of his strength. His determination to keep them alive has led him to murder Billie despite the consequences, proving that Castiel will put his own well being below theirs. He has also chosen to trust them more than his angelic siblings, given their history of deceiving Castiel and their very contrasting beliefs. Most remarkably, Castiel continues to be a forgiving, loving and gentle angel whenever he can. His current desire to undo his past sins and mistakes has compelled him to make a change.
Exploded at the molecular level by Lucifer, whose vessel at that point was Sam Winchester, in revenge for striking Michael, whose vessel was Adam Milligan, with holy fire during the Battle of Stull Cemetery. Resurrected by God as a Seraphim as a reward for his role in stopping the Apocalypse.
Makes a deal to give up his life to save Jack Kline with the Shadow promising to come when Castiel is truly happy. After Castiel admits his love for Dean and experiences true happiness, the Shadow opens a portal to the Empty and absorbs both Castiel and Billie, drawing them into the Empty. He is apparently resurrected by Jack after he becomes the new God as Bobby Singer tells Dean that Castiel helped Jack to reshape Heaven for the better.
- Castiel and Dean – Castiel and Dean are best friends. It was said by Castiel himself that they "share a more profound bond" compared to his relationship with Sam. Castiel had secretly always been in love with Dean, but believed it to be unrequited and therefore never admitted it, until circumstances forced him to speak it aloud, allowing him to experience a moment of true happiness.
- Castiel and Sam – Castiel and Sam are good friends. Both express an understanding towards one another as experienced through the understanding of self-sacrifice they've shared towards each other and to Dean.
- Castiel and Bobby – Castiel and Bobby are friends. Castiel acts generally amiable towards the older hunter.
- Castiel and Meg – Although Castiel and Meg are opposite sides, they both have an unusual connection to one another and are shown uncommonly to have a possibility for romantic interest.
- Castiel and Crowley – Like with Meg, Castiel and Crowley are opposite sides but they have occasionally worked together, most to Castiel's irritation.
- Jack and Castiel – Castiel and Jack are uncle and nephew. Like Sam and Dean, Castiel acts as a parental figure to the young Nephilim.
- Castiel's minor relationships – Castiel's other relationships he encounters.
- Season 3
- Season 4
- Lazarus Rising
- Are You There, God? It's Me, Dean Winchester
- In The Beginning
- Metamorphosis (mentioned only)
- It's the Great Pumpkin, Sam Winchester
- I Know What You Did Last Summer
- Heaven and Hell
- Death Takes A Holiday
- On The Head Of A Pin
- It's A Terrible Life (mentioned only)
- The Monster at the End of This Book
- Jump the Shark (mentioned only)
- The Rapture
- When the Levee Breaks
- Lucifer Rising
- Season 5
- Season 6
- Season 7
- Season 8
- We Need To Talk About Kevin (mentioned only)
- What's Up, Tiger Mommy? (seen in Dean's flashbacks of Purgatory)
- Blood Brother (seen in Dean's flashbacks of Purgatory)
- Southern Comfort (mentioned only)
- A Little Slice of Kevin
- Hunteri Heroici
- Torn and Frayed
- Everybody Hates Hitler (mentioned only)
- Remember the Titans (mentioned only)
- Goodbye Stranger
- Taxi Driver (mentioned only)
- Pac-Man Fever (mentioned only)
- The Great Escapist
- Clip Show
- Season 9
- Season 10
- Season 11
- Out of the Darkness, Into the Fire
- Form and Void
- The Bad Seed
- Baby (voice only)
- Our Little World
- The Devil in the Details (himself and possessed by Lucifer)
- Into the Mystic (possessed by Lucifer and mentioned)
- Don't You Forget About Me (mentioned only)
- The Vessel (possessed by Lucifer and himself)
- Beyond the Mat (possessed by Lucifer)
- Hell's Angel (possessed by Lucifer and himself)
- The Chitters (mentioned only)
- Don't Call Me Shurley (mentioned only)
- All in the Family (possessed by Lucifer)
- We Happy Few (possessed by Lucifer and himself)
- Alpha and Omega
- Season 12
- Keep Calm and Carry On
- Mamma Mia
- The Foundry
- American Nightmare (mentioned only)
- Rock Never Dies
- First Blood
- Lily Sunder Has Some Regrets
- Regarding Dean (mentioned only)
- Stuck in the Middle (With You)
- Somewhere Between Heaven and Hell
- The British Invasion (voice and mentioned only)
- The Memory Remains (voice and mentioned only)
- The Future
- Twigs & Twine & Tasha Banes (mentioned only)
- There's Something About Mary (mentioned only)
- All Along the Watchtower
- Season 13
- Lost & Found (corpse only)
- The Rising Son (mentioned only)
- The Big Empty
- Advanced Thanatology
- War of the Worlds
- The Scorpion and The Frog (mentioned only)
- The Bad Place (mentioned only)
- Breakdown (mentioned only)
- Various & Sundry Villains
- Devil's Bargain
- Good Intentions
- A Most Holy Man (mentioned only)
- Bring 'em Back Alive
- Unfinished Business (mentioned only)
- Beat the Devil
- Let the Good Times Roll
- Season 14
- Stranger in a Strange Land
- Gods and Monsters
- The Scar
- Mint Condition (mentioned only)
- Nightmare Logic (mentioned only)
- Optimism (mentioned only)
- Unhuman Nature
- The Spear
- Damaged Goods (mentioned only)
- Prophet and Loss
- Peace of Mind
- Don't Go In The Woods (mentioned only)
- Game Night
- Jack in the Box
- Season 15
- Back and to the Future
- Raising Hell
- The Rupture
- Atomic Monsters (mentioned only)
- Proverbs 17:3 (mentioned only)
- Golden Time
- Last Call
- Our Father, Who Aren't in Heaven
- The Trap
- The Heroes' Journey (mentioned only)
- The Gamblers
- Galaxy Brain
- Destiny's Child
- Last Holiday (mentioned only)
- Gimme Shelter
- Drag Me Away (From You) (mentioned only)
- Inherit the Earth (voice, mentioned and flashback)
- Carry On (mentioned only)
- Ghostfacers (special webisode)
- A Very Special Supernatural Special (archive footage)
- Supernatural: Heart of the Dragon (non-canon)
- Supernatural: The Unholy Cause (non-canon)
- Supernatural: War of the Sons (non-canon)
- Supernatural: Cold Fire (non-canon)
- Supernatural: The Men of Letters Bestiary: Winchester Family Edition (non-canon, mentioned only)
- Castiel has killed one main antagonist, Raphael in season 6, and has defeated a main antagonist, Metatron in season 9. He has also defeated one secondary antagonist, Pestilence in season 5, and killed a secondary antagonist, Bartholomew in season 9. He played a major role in killing another main antagonist when he helped Dean kill Dick Roman in season 7, which sent both Dean and him to purgatory. He later killed the secondary antagonist Belphegor in season 15 and was directly responsible for the death of the secondary antagonist Billie in the same season.
- Castiel can be seen as the main antagonist of season 6 along with Raphael and Crowley, though some argue him to be more of an anti-hero in that season.
- Castiel's name is considered a variant of the name "Cassiel", who in angelology, is the angel of Thursday with his month being November. This name was possibly chosen for the character in Supernatural because the show (then) aired on Thursday nights.
- Jim Michaels jokingly tweeted that Castiel's nickname is spelled as Kaz.
- He is among the most popular characters of the show; in fact, he was spared from the writers' original plans of being permanently killed off at least twice - in On The Head Of A Pin and Swan Song for this very reason. The actor who performs his role, Misha Collins, was promoted to regular status in Seasons 5, 6 and 9, which only two other actors, Katie Cassidy and Lauren Cohan, had previously held. Collins has also been the only other actor than Jared Padalecki and Jensen Ackles (Sam and Dean's actors) to be included in the group seasonal promotional pictures until Season 8, which also includes Crowley.
- A third attempt to kill Castiel off occurred in Season 7, but that, too, had to be undone.
- Castiel is the most recurring angel in the series, despite only having a six-episode story arc in the original planning; his appearances have surpassed even Bobby Singer's.
- Season 4 is the only season Castiel appears in where he doesn't kill another angel.
- Castiel has killed every species of angels except for the Cherubim and Seraphim.
- Co-star Jared Padalecki does not believe Supernatural can exist without Misha or Castiel.
- Because he believed his character's tenure on the show would be short, actor Misha Collins used a deep, gravelly voice while portraying his character that he believed fit Castiel's introduction as a powerful entity. He later came to regret this choice when Castiel became a recurring character, as the voice Collins used for Castiel hurt his throat. In their scenes on-set together, he and Ackles reportedly compete with one another in who can use a deeper voice.
- According to an interview in 2009, the role of Castiel was disputed between Misha Collins and Mark Pellegrino. Misha ultimately won, while Mark earned the role of Lucifer about a year later. Misha himself would play Lucifer about six years later after the latter took over Castiel's vessel.
- Despite being the one to confirm the existence of angels to Sam and Dean, he is the second angel to be revealed in the series as Gabriel has the distinction of being the first one to appear.
- Castiel is known to have used three vessels: an unnamed woman in the 19th-century, Jimmy Novak, and his daughter, Claire Novak. Castiel has revealed that he could also use Sam Winchester (and by extension, presumably Dean Winchester too) if he had his permission.
- After becoming a "mutated angel" by absorbing all of Purgatory's souls, the wing flapping sound is no longer heard when Castiel teleports, insinuating that it affected his true form.
- Upon shifting Sam's condition onto himself, after he awakes, in his insanity he becomes obsessed with bees. In There Will Be Blood, he admits to wanting to watch them. In Survival of the Fittest Dean mentions he once appeared on the Impala naked and covered in bees. In the same episode, Castiel offers Crowley honey.
- Despite the Leviathans' ability to kill angels easily, Castiel is one of the few beings that has been able to hold his own for at least a short time against them, sharing this with Sam, Dean, and the Alpha Vampire. This may be because he is a Seraph, a stronger class of angel than the ones that previously faced the Leviathans. Castiel was able to single-handedly hold his own against two Leviathans in Purgatory until Dean was able to decapitate them. However, he is unable to defeat them on his own and has been nearly killed by Leviathans in Purgatory on at least two occasions. He did however partake in killing Dick Roman in a team effort with Dean.
- Castiel, like all members of Team Free Will, has been to Hell, Purgatory and Heaven. Only Dean has been to Avalon in addition to the three previously mentioned. However, Castiel (along with Jack) has, due to the natural order of death for angels, been to the Empty.
- Before losing his grace, Castiel was the only known Seraph in Supernatural. He lost this power when Metatron stole his grace. He eventually regained angel powers with Theo and later Adina's grace and became a Seraph again when he regained what was left of his own grace.
- At some point Castiel learned how to steal and drive a car. As he can no longer teleport without his wings, he stole a car in Road Trip to reach Dean. Ironically the car color matches his first trench coat, which explains why he liked it. However, the first time Castiel is seen driving on-screen is in the episode Meta Fiction.
- In Season 12, Castiel has begun using a truck that he stole instead of his signature car.
- Following his resurrection in Season 13, Castiel begins driving a series of different vehicles instead of just one consistent car or truck, though he does have a truck that he uses for several episodes before it disappears again.
- After years of being frustrated by Dean's repeated references to movies or TV shows, Castiel has finally gained an understanding of them in Meta Fiction, thanks to Metatron granting all his pop culture knowledge into Castiel's brain. Before this, his default response was to say "I don't understand that reference" and he shocked Sam and Dean by understanding a Star Wars reference when he displayed his new knowledge.
- During his time in Purgatory, Castiel sported a beard, though his facial hair never changed on Earth. He shaved it off after returning to Earth.
- Castiel's signature trench coat look was homage to the anti-hero con man magician, John Constantine of the DC/Vertigo comics. Eric Kripke stated that he had originally wanted John to be a recurring character in the Supernatural series, but was told no. Instead, Kripke created Castiel and dressed him in a trench coat as homage.
- It is confirmed that Castiel's vessel Jimmy Novak is in fact dead, making Castiel the only known angel possessing a dead body due to the angelic need for permission. Michael became the second Angel and only Archangel to possess a dead body as his vessel in Inherit the Earth.
- Castiel has also begun to refer to the corpse as "his body" rather than "his vessel".
- Also, due to losing his grace and becoming a human while in this body, the body became effectively his; even after he regained his grace and became an angel again, he retained the ability to give permission to other angels to possess his body.
- In the episode Red Sky at Morning, one of the words Sam reads in the incantation to summon the ghost at the graveyard is the name "Castiel". This was in Season 3, before Castiel ever appeared.
- Castiel is the first angel to have his vessel possessed by another angel, while he himself is still inside of it. This occurred when he said "yes" to Lucifer.
- Like Sam, John and Bobby, Castiel has shown the ability to overpower a being possessing him. Castiel managed to overpower Lucifer briefly, but stated that it took all of his strength just to hold him back from killing Sam and could not eject him as a result. Unlike Sam, Castiel noticeably struggled with Lucifer for control while Sam was able to hold Lucifer back to the point he could move around and throw himself into the Cage.
- It is implied in Don't Call Me Shurley that God's favorite angel is Castiel, as pointed out by Metatron.
- Though in that same episode, while God confirms that he was the one who resurrected Castiel each time he died, it is implied that he is disappointed in him as he told Metatron "I rebuilt Castiel more times than I can remember and look where that got me!"
- As of Season 15, Castiel is likely no longer the favorite because of his attempts to help the Winchesters defeat him. Indeed in Unity God expressed anger towards Castiel and his rebelliousness.
- As pointed out by Sam, Castiel's vessel is very strong, having held the Seraph for years, and, at one point, withstanding a simultaneous possession by an Archangel and a powerful demon. Despite still being possessed by Lucifer, after a considerable length of time, it appears to be intact, as opposed to Lucifer's temporary vessel, which began to deteriorate almost immediately. Castiel's vessel also withstood millions of souls from Purgatory and many Leviathans for some time before it started to degrade. In We Happy Few, Castiel tells the angels that Lucifer possessing him is actually burning both him and his vessel out despite not showing visible damage, indicating that he is strong enough to last longer than a regular vessel.
- When going undercover as an FBI agent, Castiel has adopted Dean's habit of using pop culture references as his aliases. However, instead of classic rock, he uses pop stars, not seeming to see a difference when confronted by Dean when he dubs the Winchesters Agents Aguliar and Spears. Castiel has also used Agent Beyoncé in The Foundry, prompting Crowley to dub himself Agent Jay Z.
- Chronologically speaking, Castiel is the first angel to use vessels of both genders. In 1901, Castiel was shown to use a female vessel while working with Ishim. However, unlike the other members of Ishim's flight, Castiel did not keep this vessel for an unknown reason.
- Castiel sought to find God in Season 5 though had no luck and gave up his search. He eventually met him in Alpha and Omega.
- This makes him one of the seven angels to personally meet God though they had no known conversations on-screen.
- Coincidentally, he already met him in Season 4 but was unaware of his identity.
- In later seasons, Castiel uses his angel blade to kill demons rather than his smiting power, even after he becomes a Seraphim again. Until Season 13's Various & Sundry Villains, he hadn't used smiting since he smote Theo in Season 9's Holy Terror, a span of over four years. The last time he used smiting to kill a demon before Various & Sundry Villains was in Season 8's Goodbye Stranger. No explanation is ever given for Castiel's change in killing method, particularly after he gets his grace back and no longer has to worry about it being depleted.
- In Scoobynatural, Castiel implies he is now married to the Djinn Queen after getting the Fruit of the Tree of Life.
- This marks the first union between a monster and angel.
- He is the first character to kill an Alternate version of himself, since Kaia was revealed to have been saved by Dark Kaia, after Dark Kaia almost killed her by accident.
- As of The Big Empty, Castiel was the first being to escape The Empty.
- In the Studio & Network draft of Peace of Mind, Castiel reveals he watches Riverdale, a fellow The CW show.
- As seen in The Heroes' Journey, Garth named one of his twin sons after Castiel. The baby appears to also have Castiel's tendency to give Dean weird stares.
- According to God in Unity, this version of Castiel is the only one that rebelled instead of doing what he was supposed to do after resurrecting Dean from Hell in Season 4.
- Misha Collins stated in a 2020 panel that Castiel's wings are rainbow.
- Castiel is canonically bisexual in the series. He was shown to be romantically interested in the demon Meg, had a sexual encounter with the reaper "April Kelly", and was attracted to the angel Hannah. In his "human" life as Emmanuel, he was also married to a woman. But he eventually confessed his love for Dean in the season fifteen episode Despair. The romantic nature of his feelings for Dean has been confirmed by Misha Collins, who described Castiel's final speech to Dean as a "homosexual declaration of love". However, Misha also confirmed that these feelings are one-sided, as Dean is straight.
- Castiel is thus the one main character and angel character in the series to be confirmed as LGBT+.
- Misha Collins' Twitter
- Lazarus Rising
- Are You There, God? It's Me, Dean Winchester
- Sympathy for the Devil
- Swan Song
- The Third Man
- The Man Who Would Be King
- The Man Who Knew Too Much
- Hello, Cruel World
- The Born-Again Identity
- Reading Is Fundamental
- Survival of the Fittest
- Don't Call Me Shurley
- Family Matters
- Road Trip
- Meet the New Boss
- Jim Michaels' Twitter
- Fan's Twitter
- Misha Collins Confirms 'Destiel' is Canon, Says Castiel Made a 'Homosexual Declaration of Love'
- Misha Collins blames 'rogue translator' for changed viral scene: 'I'm irked'