"I'm glad you had a little taste of freedom. What I said was... I'm always 10 steps ahead. I said you cross me, I crush you. You hit me, I hit you back twice as hard. You make me your dog, I'll make you my slave. That chain around your neck? Was nothing. A stylish accessory. This vessel... That's your true prison. It's been warded with runes and spellwork from the Cage carved into every molecule. In there? I own you. I'm just getting started. So... I'm gonna put you back in your hole, and then I'm gonna go find your spawn, and then I'm gonna rip him apart while you watch. And then? I'm still just getting started."
— Crowley, "Between Heaven and Hell"
Sam & Dean Winchester have encountered all sorts of monsters and entities across their travels. Here are the ones who prove to be the most audacious and charismatic of them all.
All spoilers are unmarked. You Have Been Warned!
- Azazel is the mightiest of the Princes of Hell and one of the first demons made by Lucifer. The first to find Lucifer and formulate the plan to free him, Azazel begins cultivating the special children and shaping their lives to enhance their psychic powers, including Sam Winchester. Later completely outwitting the Winchesters and defeating them, he convinces their father John Winchester to sacrifice his life to bring Dean back to life, eliminating his greatest enemy and sending John to Hell so the demons can begin working on breaking the 66 Seals. Azazel manipulates the psychic children further into a gauntlet to determine who will open the gates of Hell to free Lilith herself, all for the sake of the winner destroying her to eventually unleash Lucifer while being ready and available as the fallen angel's vessel. Azazel remains one of the most dangerous and personal enemies the Winchesters had ever faced, whose charm and ruthlessness have rarely been matched with his love for his demon children making him a dark mirror to John Winchester himself.
- The demon who takes her host's name of Meg Masters is the "daughter" of Azazel, well versed in manipulation by her father. Playing at being a young woman on the run to lure in others, even Sam Winchester, Meg later returns to use the Winchester brothers to lure out their father John before steadily eliminating multiple allies of the Winchesters. Later exorcised and returning, Meg possesses Sam himself and bides her time to ruin his name and destroy him and Dean again. After Lucifer is foiled, Meg becomes an uneasy ally, assisting the Winchesters for her own purposes against Crowley while developing a connection with the fallen angel Castiel, even sacrificing her own life to help get them to safety.
- Gabriel is the youngest of the four Archangels who chose to leave Heaven, taking up the mantle of the trickster god Loki. Serving as a recurring foe of the Winchesters, Gabriel outwits them several times before allying with them against the monstrous Lucifer. Seemingly killed by Lucifer, Gabriel gives crucial information to Sam and Dean that results in Lucifer's defeat. Revealed to have faked his death, Gabriel was sold out to the Prince of Hell Asmodeus by the real Loki, later getting his flair back and incinerating Asmodeus, taking his revenge on Loki, and helping the Winchesters rescue their mother and surrogate son Jack from the Apocalypse World, even sacrificing his life to allow them to safely make it back to their world. With a chaotic and poetic sense of humor, and a respect for humanity that sets him apart from his fellow Archangels, Gabriel stood out as one of the most hilarious, yet craftiest characters in the series.
- Crowley starts as a lowly demon salesman who realizes Lucifer's intentions to wipe out demonkind after he's finished off humanity. Assisting the Winchesters to help bring Lucifer down, Crowley later relies on his wits and power to ascend to become the King of Hell where he becomes the Winchesters' deadly enemy. Using Castiel to assist him into mining Purgatory for the power of the souls within, Crowley usually manages to stay a step ahead of the Winchesters, frequently coming out on top and strengthening his position while eliminating his enemies and rivals. Upon the return of Lucifer, Crowley manages to even outwit and briefly helps imprison the fallen angel before his escape. Even at the end, Crowley manages to achieve a victory against Lucifer by sacrificing his own life, proving that when one faces Crowley, even when he loses, he will win in the end.
- Death is the oldest of the four Horsemen and the boss of all Reapers. Summoned by Lucifer to assist him in the Apocalypse, Death slowly engineers the Archangel's downfall by sparing the life of Dean Winchester and giving him his ring so that he can trap Lucifer in his Cage again. Death returns to managing the flow of life and death and keeping the natural order in balance, setting up a trial for Dean in exchange for Sam's soul by giving him his job for a day so he can teach him a lesson about the Winchesters' continual defiance of cosmic laws. He even gives the Winchesters the knowledge and means to stop an overpowered Castiel after he declares himself the new God and later to keep the Darkness imprisoned by the Mark of Cain. Unfailingly polite with a lethal distaste for rudeness, Death is courteous to every soul he claims and always instills fear and respect in Sam and Dean.
- The Alpha Vampire is one of the oldest monsters in existence and the progenitor of the entire vampire race, whom he considers his "children". When captured by a group of hunters, the Alpha taunts his captors and easily escapes. Later returning after having forged an alliance with the Leviathans, the Alpha accepts Sam and Dean's warning that his new allies are planning on backstabbing him, gifting them his blood to use as part of a weapon. The Alpha finally infiltrates and nearly destroys the British Men of Letters when they attempt to wipe out all vampires in America, gracefully conceding his defeat when outmaneuvered by Sam. One of the most dignified and intelligent monsters in the series, the Alpha proved to be a formidable foe.
- The angel Metatron, Scribe of God, fled Heaven to live on earth for millennia. When approached by the Winchesters, Metatron manipulates them to gain access back to Heaven, taking it over for himself and ejecting all angels to write a "new story" with himself as the new God, playing on the angel Gadreel's guilt and shame to utilize him as an assassin. Later escaping justice even as a human, Metatron learns the value of existence and stands up to even God to help defend the world from the Darkness Amara before sacrificing himself for the Winchesters against her.
- Cain, the Father of Murder, is the founder and former leader of the Knights of Hell. Sacrificing his own soul to save his brother Abel's in a deal with Lucifer, Cain was known as "the best at being the worst," leading his demons to countless dark victories as one of the most feared beings alive until he fell in love with a woman named Collette and put aside evil to marry her. When she was taken, Cain slaughtered the Knights save his former protege Abaddon, living in peace until Dean Winchester arrived for help in destroying Abaddon. Taking up violence again while leaving Dean his Mark and the promise to stop him, Cain later resurfaced to wipe out his tainted bloodline, easily luring Dean to him for a final battle with Cain embracing his final end with nothing less than dignity and acceptance.
- Rowena MacLeod is a powerful witch and the mother of Crowley himself. Having lived centuries, Rowena is just as resourceful as her son, wasting no time in manipulating demons to earn her freedom when Crowley holds her hostage and frame an ally for treachery before eliminating him. Rowena is constantly able to remain a step ahead of all sides, playing them against one another for her benefit until Lucifer betrays her for her aid, prompting her to hide her revival and continue to dodge the others, even helping to trick and trap the Darkness herself. Rowena ends up sacrificing herself to seal Hell after redeeming herself, but turns even this to her advantage and becomes the new Queen of Hell which she begins to reshape into a gentler place without torture.
- Arthur Ketch initially appears to be a psychopathic mercenary with a love for killing, but later shows himself to be a more complex individual. Working for the British Men of Letters, Ketch is sent to the US to clean up the Winchesters "mess", killing a psychic they had just saved, and wiping out everyone at a secret facility to avoid government involvement. Executing his colleague when he rebels, Ketch begins to enact the BMOL's plan to exterminate every American hunter, brainwashing Mary Winchester into a killing machine to aide him. After being killed by Mary, Ketch resurrects himself and works for Asmodeus to hunt down Lucifer out of fear of the catastrophe that would result from the Devil roaming the earth. Growing tired of Asmodeus mistreating him, Ketch leaves his service with Gabriel in tow to deliver him to the Winchesters, and goes with Dean to the Apocalypse World to help him retrieve Mary and Jack, and leads the survivors back to the main world. In a series where the heroes confront entities with world-ending capabilities, Ketch proves that one need not have supernatural powers to be a threat to the Winchesters.
- Season 15 (Ghostpocalypse arc): Belphegor is a low-ranking demon who took advantage of God opening all of the doors to Hell to make a play for power. Possessing the body of the recently deceased Jack Kline, Belphegor secures his survival against Team Free Will by offering his services, such as decimating a hoard of zombies attacking them. He continues assisting the hunters with the Ghostpocalypse created from the billions of escaped souls, all the while retaining a friendly and affable demeanor. The heroes agree to his suggestion to perform a barrier spell, which quarantines the ghosts within a mile radius. Upon discovering the barrier is a temporary measure, Belphegor's next plan is to return to Hell to find Lilith's Crook and use it to draw all the souls back into Hell, while requesting Castiel to accompany him as a bodyguard, and despite Castiel's suspicions gets him to unlock a box containing the item they seek. When Belphegor's rival Ardat shows up, Belphegor take advantage of Castiel engaging her to kill his rival. Even when his true intentions are exposed, Belphegor merely blows Castiel back and activates the artifact, very nearly succeeding in absorbing billions of souls.
- "The Curious Case of Dean Winchester": Patrick is a centuries-old warlock from Ireland who fuels his immortality by playing a game of poker with people for their years when not spending his days stealing cars and swiping expensive jewelry for the fun of it. When Bobby and Dean both lose a game to him, Patrick remains a good sport about it, allowing Sam to win their years back fair and square even after they tried to kill him, while also occasionally sparing an utterly hopeless opponent. Having also gifted his lover Lia with immortality, Patrick also honors her wish not to linger for eternity by allowing her to play against him.
