Demons

Demons are malevolent spirits that are the direct opposites to Angels. They are created from human souls that have endured extensive torture in Hell by Alastair and other demons. In this process, they become corrupted, extremely evil, and also very powerful. Similar to Angels, they require a Vessel to walk the Earth, though are able to roam in their smoke form. The species as a whole functions as the series' primary antagonists and are the most recurring supernatural creatures in the series.

History
After humans were fully evolved, God created a paradise on Earth called the Garden of Eden. He placed humanity in the Garden, and declared them his favorite creations.

He told all the angels in Heaven to bow down before the humans, and serve them. The archangel Lucifer refused to bow down before a species that was younger, and inferior to him. He claimed that they were "flawed, and murderous." He declared war against God, and was eventually cast down to Earth.

God placed Gadreel (his most trusted angel) to guard Eden from the fallen Lucifer. Lucifer somehow managed to break past Gadreel's defense, and sneaked into the garden. As a payback to God, he corrupted Lilith's soul, and made her into the first demon.

Lucifer, still in the garden, corrupted the minds of the humans, and tricked Adam and Eve into eating the forbidden fruit. God cast humanity out of the Garden for disobeying him.

Following the creation of Lilith, Lucifer personally created four demons named Azazel, Ramiel, Dagon and Asmodeus. These four would become known as the Princes of Hell and were Lucifer's heirs and generals of demonic armies.

Adam and Eve had two sons, named Cain and Abel. Lucifer was able to manipulate Abel into listening to him, rather than God. Cain saw what Lucifer was doing, and offered his own soul, so that Abel could go to Heaven. Lucifer agreed to the deal, but Cain had to be the one to kill Abel.

Cain obeyed, and was given a mark in return. This mark would eventually transform Cain into a demon. On Lucifer's orders, Cain trained more demons, eventually creating an army known as the Knights of Hell.

In retaliation, God created a personal cage for Lucifer, which was locked by 66 seals. Ironically, the last seal that needed to be broken, was the death of Lilith, the first demon he created, and the reason he was placed in Hell.

At some point before being locked into the cage, Lucifer created the four Princes of Hell, Azazel, Ramiel, Asmodeus and Dagon to serve as the rightful heirs to his throne and to lead demonic armies in the war against Heaven.

Soon after, wicked and evil humans would be sentenced to Hell upon death. There, their souls were tortured, twisted and corrupted, and they became demons. Some of these demons made deals on Earth, condemning more souls to Hell, where they too would be corrupted into demons.

Story
"It might take centuries, but sooner or later hell will burn away your humanity. Every hell-bound soul, every one turns into something else. Turns you into us."

- Ruby to Dean

Although an ordinary demon is featured as a villain of the week in the fourth episode of the series, "Phantom Traveler", demons do not become actively involved in the show until the introduction of Azazel's "daughter"—possessing a girl named Meg Masters—in the second half of the season. She follows Sam and Dean Winchester, and later unsuccessfully sets a trap for them using their father. Following the release of hundreds of demons from the Devil's Gate at the end of Season 2, demons become the greatest, most common enemies the Winchester Brothers face in the series. At the same time, Dean Winchester kills Azazel with the Colt, creating a power vacuum.

Due to Azazel's death, the demons are initially disorganized and unable to execute their master plan. Some demons want Sam to lead them, while others follow Lilith. By the beginning of Season 4, however, Lilith has taken control of most of the demons and directs them to break the 66 Seals needed to free Lucifer. Under her direction, the Seals are broken, and Lilith allows Sam to kill her, thus breaking the Final Seal and setting Lucifer free. Throughout Season 5, Lucifer has command over nearly all demons. Dozens sacrifice themselves to assist him in raising Death. Others serve the Horsemen Pestilence and Famine, as well as the Whore of Babylon. Eventually, Lucifer is defeated and banished back to Hell.

In Season 6, in the aftermath of Lucifer's re-imprisonment, most demons have fallen under the command of Crowley, the current King of Hell. However, some demons, such as Meg, oppose his rule. Throughout Season 6, Crowley and his demons secretly assist Castiel in finding a way to open the doors to Purgatory in order to gain access to the millions of monsters souls inside. They succeed but Castiel betrays Crowley and absorbs all the souls for himself.

During the course of Season 7, the demons take a backseat to the Leviathans as the series' main antagonists. Under Crowley's orders, the demons refrain from attacking the Winchesters, so that the boys can defeat the Leviathans though the Winchesters come into conflict with rogue demons and ones hunting Castiel. However, with the death of the Leviathan leader Dick Roman at the end of the season, the demons are now poised to return to their original role as enemies of the Winchesters, having aided in finishing the last of the Leviathans on Earth.

At the start of Season 8, the Winchesters learn of a second tablet that holds the key to banishing all demons from Earth and closing the Gates of Hell forever. Their quest puts them in direct conflict with Crowley. Through the season, Sam and Dean come into conflict with the demons multiple times over Crowley's various goals. Eventually, after the Winchesters complete the first two of three trials needed to seal the Gates, Crowley keeps demons away from them to keep them from being used in the trial, but Sam and Dean capture him to cure him as the third trial. Crowley starts to become human, but Sam is convinced by Dean to stop after he learns from Naomi that Sam will die if he completes the trials. During the season, the Winchesters occasional enemy/ally Meg is killed. The demon Abaddon arrives in 2013 from 1958 and is defeated by Sam and Dean, but not killed. She eventually escapes after the Winchesters try to use her as the third trial and starts opposing Crowley's rule, wanting a "regime change." Sam manages to defeat her when she tries to kill Crowley, but she merely flees her vessel after it is set on fire with Holy Oil and is not killed.

In Season 9, Crowley is held captive by the Winchesters at the Men of Letters base and ultimately offers a deal in exchange for the name and location of every demon on Earth. At the same time, Abaddon has a ritual performed to have her vessel Josie Sands restored and begins a crusade to take over Hell and Earth. Her first attempt to kill the Winchesters fails thanks to the angel Gadreel. Abaddon has since been reshaping Hell in Crowley's absence, making it more chaotic and voiding all deals, taking the souls early. After Gadreel takes full possession of Sam, Dean makes a deal with Crowley to save him: in exchange for his freedom, Crowley helps Sam expel the angel. Crowley then starts a war against Abaddon for rule of Hell. To this end, he forms a reluctant alliance with Dean to find the First Blade, the only weapon that can kill a Knight of Hell. The two locate the retired demon Cain, the Father of Murder and founder and slaughterer of the Knights of Hell. Cain eventually agrees to help, giving Dean the Mark of Cain so that he can wield the Blade and the location of the First Blade which is at the bottom of the ocean.

Even though Dean understands that Crowley was just using him to get the Blade, the two maintain their alliance as they need each other to defeat Abaddon who is the greater enemy. Eventually, working together, the Winchesters and Crowley find the First Blade, but Crowley takes it until they can locate Abaddon as he doesn't trust Sam and Dean not to try to kill him. Dean becomes obsessed with hunting and killing Abaddon and Sam joins him in this after learning that Abaddon is stealing souls to create an army of demons loyal only to her. Abaddon, using Crowley's son Gavin as leverage, forces Crowley to help her trap and kill the Winchesters. Crowley leads them to the First Blade, but subtly warns Dean that it is a trap when telling them where to meet him. In a final confrontation, the Mark of Cain grants Dean immunity to Abaddon's power and telekinesis, allowing him to gain the upper hand and finally kill her.

Sam and Dean leave Crowley alive, but take the First Blade with them. Crowley however escapes with his son to spare him from returning to his time and dying. Crowley later reveals that Cain, the Father of Murder did not want to kill and committed suicide but the Mark of Cain proved too strong, forcing his return as a demon. The same thing happens to Dean who transforms into a demon.

In Season 10, Dean has become a demon. Crowley wants Dean to rule by his side, but Dean is uninterested and proves too out of control for even Crowley. As a result, Crowley helps Sam capture Dean and saves Castiel to help deal with him. Sam manages to cure Dean of being a demon and he returns to hunting with his brother. At the same time, with Abaddon dead, Crowley regains control of Hell and punishes demons who transgressed against him, particularly by serving Abaddon. However, Crowley grows bored of his role and has to deal with the appearance of his mother Rowena who tries to manipulate him to gain power but fails. Cain eventually resurfaces, but is killed by Dean with the help of Sam, Castiel and Crowley. Eventually, Crowley helps remove the Mark of Cain from Dean's arm, but comes under attack by Castiel who is under a spell while the Darkness is accidentally released.

In Season 11, Crowley has his demon minions take care of a young Amara, but they find her difficult and constantly hungry, going so far as to consume her demon nanny and anyone who upsets her. She eventually escapes.

Crowley later agrees to help Sam and Dean contact Lucifer. Crowley sends two demons to capture Rowena so she can look up a way to summon Lucifer using the Book of the Damned. The meeting ends with Lucifer escaping in Castiel's vessel and Rowena getting killed after having been secretly working for the archangel. Lucifer tortures Crowley until he becomes an obedient servant, while most of the demons willingly go back to serving him. A few go rogue for their own safety.

In We Happy Few, Crowley is back on the throne and asks the demons to join him defeat Amara to make Hell great again. Unfortunately, they laugh at him, saying he has made hollow promises so far. However, a big number of demons in their smoke form, soon joined by Crowley, also in his smoke form, make a collective attack on Amara to weaken her for God and Lucifer to finish her off. They succeed but the final stage of the plan fails, and Amara defeats God. The demons presumably returned to Hell in the aftermath. They are also said to have raided Crowley's stash of souls.

In Season 12, the demons are back to serving Lucifer, with two shown taking orders from him and defiantly rejecting Crowley as their king. After Lucifer is defeated and presumably sent back to his Cage, the demons return to Crowley. Some are ordered to study The Cage and use its structure to presumably create chains that can bind Lucifer. A few years back, the demons also found Nick's body and restored it for future use.

It's also revealed that the Princes of Hell, long thought dead, are in fact still alive aside from Azazel who had been killed by the Winchesters years before. While on a mission for the British Men of Letters, the Winchesters come into conflict with and kill Ramiel. Shortly thereafter, another Prince, Dagon, begins working for Lucifer again as the protector of his son. Dagon was eventually killed by Castiel while he was empowered by Lucifer's son, leaving Asmodeus as the only living Prince of Hell.

Discontent with Crowley continues, and two demons do eventually discover Lucifer and try to free him, but neither are aware that Lucifer's true prison is his own vessel, which Crowley has complete control over. When Crowley presents the now submissive Lucifer to an assembly of demons, Lucifer secretly threatens them to obey him and not Crowley. One of the demons, Drexel, eventually offers to help Lucifer break free from the system which gives Crowley control over Nick's body. When Drexel succeeds, the demons flock back to Lucifer while Crowley is presumably dead.

Loyalty falls completely to Lucifer when Crowley does end up dead at his own hands, in order to lock Lucifer away. The throne is vacant as a result.

In Season 13, Prince of Hell Asmodeus takes the throne of Hell as a temporary substitute for the absent Lucifer. Asmodeus commands the demons to retrieve Lucifer's newly-born son Jack so the boy may inherit his legacy as heir to the throne of Hell and also set free the Shedim. Asmodeus' plans are foiled by Sam and Dean Winchester.

Characteristics
"They don't want anything, just death and destruction for its own sake."

- Dean, describing demons

Demons are the result of human souls going to Hell and being tortured until no humanity is left in them, thus turning into demons - dark, malicious spirits that revel in pain, chaos, and death. According to Ruby, most demons forget what it means to be human. Some have even forgotten that they were once human. In general, demons engage in torture and destruction because it is fun or to avoid being tortured themselves. Some demons, however, are true believers in Lucifer's agenda to "cleanse" Earth, and actually consider themselves morally superior to humans.

There are many ways of becoming a demon, from making a deal with a Crossroad Demon, to being a witch, and making a deal with another demon. They manifest on Earth in the form of a long, slender cloud of black smoke. Crowley appears as the only exception, appearing as a blood-red cloud. Their true forms have not been shown onscreen, however Dean has seen their true forms, before he was taken to Hell. He says they look horrible even going as far to call Ruby "one ugly broad." However, their true form has been hinted at by Azazel's cloud showing a skull-like face, and when a demon is killed by any blade it reveals a skeletal fiery organ beneath, suggesting that a demon's true form is a fiery skeletal form wreathed in fire and smoke.

Once a soul becomes a demon, it gains the basic demonic powers (possession, superhuman strength, etc.) and from there, it can work its way up the ladder to positions of greater authority and power within Hell. Often when a demon has used its powers, they leave a trace of sulfur in the nearby space, or if on a person, around the victim. This can give away the demon's presence, indicating to hunters that they are hunting a demon. Very powerful demons leave much more sulfur than average, as evidenced when Azazel kidnapped Sam. Some demons are sent back to Earth to accomplish certain tasks, such as causing disasters, spreading diseases, assassinating hunters, or manipulating people into committing crimes that will get them sent to Hell. To do this, they have to take a vessel or "meatsuit" in order to physically exist.

When they possess humans, they usually enter through their mouths. On one occasion, a demon entered a human via the eyes (as seen in the episode Phantom Traveler). Possessed humans often look exactly the same as they did before possession, the only noticeable change being that their eyes will sometimes change color (black, red, white, grey, or yellow depending on the demon possessing them). Demon possession also causes a chemical change in the circulatory system of the host; demon blood is known to be a unique serum and has certain attributes when ingested. Whenever they use their powers, they leave a trace of sulfur in the form of yellow dust. Angels and other supernatural beings can see the true faces of demons underneath their vessels.

Often under possession the human begins speaking and acting like the demon would. Upon exorcism the human - if they survived - retains no memory of their time during possession (unless they have been "awake" during possession, in which case the time of possession is a nightmare for them). The possessed humans also gain the powers of whichever demon is possessing them. Unlike angels, whose possession of a human vessel has to be with the vessel's consent, demons forcibly possess humans. People suffering from stress, fear or panic can be vulnerable to demonic possession. Demons abhor the name of God (Christo).

Demons apparently cannot leave a host body if they are gagged by an encrypted gag; Sam and Dean make use of this tactic against the Phantom Traveler via blindsiding it and taping its mouth shut, while both Meg and Ruby have been gagged while undergoing torture to prevent them from fleeing their hosts.

Demons have no quarrel with killing or torturing their own kind to achieve their goals. Tom, for example, tested the fake Colt by shooting his demonic "sister" Meg. When pitted against other demons due to their individual goals, Ruby, Crowley, and Meg herself have killed their own kind without pause or remorse. High-ranking demons will casually sacrifice their underlings without hesitation. At the same time, though, some demons forge bonds with their siblings. Azazel, for example, referred to Meg and Tom as his "children" and was angered when Sam and Dean exorcised Meg and killed Tom (Devil's Trap).

It is revealed that demons, although being tortured and twisted human souls, can be cured. Father Max Thompson, a member of Men of Letters, tried to find this cure, having made several experiments, but always ending with the demons' escape. Finally, he found that it is necessary to perform it on sacred ground and use purified blood to heal a demon. He injected his own purified blood into the demon hourly eight times and after the eighth he recited the exorcism achieving the cure. Sam later used this cure successfully on Dean.

Like angels, demons tend to dress in formal wear while possessing a human, wearing dark suits in contrast to the lighter colored suits worn by angels. Some demons prefer whatever outfit the human was wearing. A notable exception is Crowley, who despises anything other than a well-tailored, dry-cleaned suit. However, demons such as Meg, Ruby and Duke prefer leather jackets. Certain crossroads demons, especially ones in female vessels, wear appealing outfits to appease their clients.

Although demons are born from twisted and tortured souls and are notorious for their vicious nature, demons under Crowley tend to act much like regular humans in that they operate in a business-like fashion and rarely exhibit unrestrained behavior. One demon explained that "You can be damned and a conscientious worker." A majority of the demons do not recall their time as a human.

It is revealed in the Season 13 episode "The Big Empty" that all demons go to a dimension called The Empty when they die.

Types of Demons
 White-eyed demons are ancient demons, Lilith being the oldest of the demon kind. They're terrifyingly powerful and they rank the highest in the hierarchy of Hell. They inspire fear in their subordinates as all other demons seem to be terrified of them. Being as powerful as they are, they were resistant to many demonic weaknesses. They were even capable of holding their own against regular angels. So far, the only known demons of this type are Lilith and Alastair.
 * -|White-eyed Demons=
 * -|Princes of Hell=

The yellow-eyed demons are the Princes of Hell, the first generation of demons created after Lilith and the rightful rulers of Hell. The four Princes are Azazel, Ramiel, Asmodeus and Dagon. Besides having a unique durability threshold and advanced telekinesis, Azazel could manipulate fire, control dreams, make electrical devices go haywire, and could even possess reapers. The initial leader of the demon army, Azazel was the designer of the master plan to free Lucifer from Hell. He was impervious to holy water and most other conventional defenses against demons, but was finally killed by the Colt. Ramiel proved invulnerable to the demon-killing knife and an angel blade and only showed vulnerability to the Lance of Michael. Currently, only Asmodeus is alive after the Winchesters killed Azazel and Ramiel and Castiel killed Dagon with the help of the Nephilim Jack.
 * -|Knights of Hell=

Knights of Hell are very powerful demons, said to be some of the first demons; handpicked by Lucifer himself, they were trained by Cain, the Father of Murder and himself the first Knight. Legend among Men of Letters had it that the archangels have destroyed all but one, but in truth Cain himself killed them. Knights possess a number of abilities not seen from other types of demons. They are also nearly invulnerable, being immune to many defenses against demons, including exorcism rites and even the demon-killing knife. The only weapon that can kill one is the First Blade. With Abaddon's death and Dean being cured, Cain was the only Knight left until Dean ended him after Cain began killing again. Red-eyed demons, more called Crossroads Demons, are one level higher than black-eyed demons, and have more powerful abilities, such as teleportation and deal making. Since red-eyed demons have the ability to teleport, they are usually stationed as crossroad demons, so they can teleport to the crossroads without having to be forcefully summoned. As crossroads demons, they make deals with humans, granting them one wish in exchange for their soul. In a period of time, normally ten years, a hellhound will be sent after the deal maker and drag them to Hell, where they will become a demon. While stationed as crossroad demons, red-eyed demons generally possess attractive females, presumably to attract men to make a deal. If favored by the Ruler of Hell, or another higher demon, red-eyed demons can be promoted from a crossroads demon to a higher position. The most common and standard class of demons on the show, black-eyed demons possess only basic powers, such as possession, super-strength and telekinesis. Effective defenses against these demons include holy water, salt, iron, a Devil's Trap, etc. Stronger black-eyed demons, such as Meg or the Seven Deadly Sins, have more resistance such as not being barred from entering hallowed ground and one demon, Astaroth, is shown to have the ability of causing internal bleeding and extensive magical knowledge, such as when she recites a ritual to exorcise Ruby from her body.Astaroth was also able to stop a bullet shot from the Colt in mid-air. Although the Knights of Hell are black eyed demons, they are far more powerful and possess much greater abilities.
 * -|Crossroads Demons=
 * -|Black-eyed Demons=
 * -|Others=

The Acheri are a type of demon that can materialize their own form without the need of the use of a vessel, generally, if not always, taking the form of little girls. They can be summoned and controlled.

Cambions are demon/human hybrids, which are created when a demon reproduces with a female human virgin, by using said human as a vessel. Jesse Turner is the only known cambion. Their powers far exceed that of any demon and grow to much greater levels when Lucifer is out of his cage.

The Daeva are a type of demon, that can materialize their own form to that of a shadow which can be summoned and employed by other demons similar to hellhound.

Tempter Demons are a type of demon that exist in an alternate reality. They have horns and sharp teeth.

Special
Throughout the course of Supernatural, the Winchester brothers have battled demons that are unique in some way. These are the known kinds:


 * The multicolor-eyed demon, Samhain, the origin of Halloween, who can be summoned through three blood sacrifices every 600 years.
 * The Seven Deadly Sins, the physical embodiment's of the eponymous sins.
 * The daeva, Zoroastrian shadow demons, who are sometimes used by other demons to attack targets, but are difficult to control, and can turn on the demon controlling them. They do not seem to require a host.
 * Disaster Demons, a demon that causes disasters, a rare type, each causes a specific type of disasters, both natural or man made as on the episode Phantom Traveler (causing airplane crashes). They are also quite unique, as their form on Earth resembles insects more than smoke, they enter their victims through the eyes, and only the irises turn black when possessing a victim. They can also possess inanimate objects such as cars and planes.
 * The Acheri, demons that appear as young girls with feline features. They do not seem to require a host.
 * Dever/Reshef - Demon of plague and pestilence and the creator of the Croatoan Virus. May be one of the demons that causes disasters. "Dever" and "Reshef" are ancient hebrew words fo "plague", metioned in the Old Testament.
 * The cambion Jesse Turner, a boy born from a human woman while possessed by a demon, was meant to become the Antichrist, destined to help Lucifer not only destroy humanity, but also destroy the Host of Heaven. Lucifer's presence on Earth increased his powers tremendously. Even though he was still a child, he was powerful enough to turn Castiel into a toy figure. However, thanks to Sam and Dean's encouragement, Jesse rejected his destiny and went into hiding.
 * The Tempter Demon is a type of demon that exists in an Alternate Universe. There are the only known type of demon to posses horns.
 * Green-eyed Demons, demons that were only mentioned one time, but never seen.
 * Orange-eyed Demons (non-canon), a rare type of demon mentioned in Bobby Singer's Guide to Hunting, Bobby compared the behavior of these demons with those of the demon who possessed his wife, Karen.
 * Moa'ah (non-canon), is a unique demonic breed of creature which is commonly found in Southern America. It's commonly found on land which supported massive carnage. According to Castiel, it was very common to be found on The Civil War battlefields where both sides (Union and Confederate) spilled their blood on fierce battles, but they somehow wiped out to the point it was no longer detected, even by the angels. It's very presence on a land is a signal of Apocalypse.

Powers and Abilities
After their spiritual decay is complete, demons develop supernatural abilities. It is unknown how demons' powers increase. However, it seems they do not gain it purely from age as Crowley is far more powerful than Meg and Ruby despite being hundreds of years younger than them.

Low-Level Powers
These abilities are possessed by all demons.
 * Demonic Possession - Like angels, most demons (only known exceptions are Acheri and Daeva) require a human vessel or "meatsuit" to travel on Earth. Unlike angels, they do not need a person's consent. Also unlike angels, demons can possess corpses. It is easier to take control of people who are in states of heightened emotions or fear. When possessing a human, demons invades their muscles, organs, bones, fluids, and brains and can also access their host's memories while possessing them (even if it is a brief possession). This also affects a host's blood, imbuing it gives it supernatural properties for as long as they are inhabited by a demon. This ability can be thwarted by Anti-possession tattoos. Also under certain circumstances, the person being possessed can regain control if his or her will is strong enough. They can also possess humans who are already possessed by an angel (and probably by another demon), but the only problem is the angel can neutralize it, because angels are naturally stronger than demons. In many cases, the demon will ride the host hard for fun and once they vacate, the host will die. Some demons appear to have preferencies when possess someone, Lilith likes to possess young girls, the Seven Deadly Sins appeared to prefer vessels guilty of the sins they embodied, and the Disaster Demons to possess people who were in a mentally weakened state caused by fear.
 * Electromagnetic Interference - Demons, like spirits, often disrupt nearby electronics with their presence. Large numbers of demons can cause thunder storms.
 * Flight - Only when in their smoke forms.
 * Immortality - Demons have an indefinitely long lifespan and an arrested aging process. They are also immune to diseases.
 * Invulnerability - Injuries that would be fatal to humans, such as broken necks or gunshot wounds, have very little - if any - effect on demons. They can only be killed by special weapons or rituals. Unlike angels they don't always heal their vessels. If the "meatsuit" receives too much damage they simply find another human to possess, leaving their former vessel to die.
 * Super Stamina - Demons never tire, and do not require food, water, oxygen, or sleep to sustain themselves. Sam states that they also do not get hot or cold and Dean states they do not need to urinate.
 * Superhuman Strength - Demons possess superior physical strength compared to that of humans; capable of physically overpowering humans and most monsters. Even lower demons can overpower hives of vampires and even killed a wendigo without the use of fire. Once, the Disaster Demon, a low-level demon, was able to ripped open an airplane hatch with over 2 tons of pressure at over 1,000 feet above the ground easily. Also lower demons can slaughter small armies of humans and rip humans to pieces with ease. The higher ranking the demon, the stronger it is. The highest ranking demons can overpower most types of angels, short of archangels.
 * Supernatural Perception - Demons are able to see hidden supernatural activity and beings, such as Reapers, ghosts, and hellhounds.
 * Super Senses - Demons have an enhanced sense of smell and taste, demonstrated as Crowley could identify Castiel was in Dean's Impala and that he and Raphael had been using dog's blood. A demon possessing a waitress claimed she could smell Sam's soul.

Mid-Level Powers
Used by some (mostly upper and some mid-tier), but not all, black-eyed demons, as well as higher-ranking demons.
 * Biokinesis - Some demons can manipulate the biology of other beings. Azazel, for example, was able to torture Dean by causing him to hemorrhage. Meg was also able to cause Crowley to cough up blood in a similar manner. Astaroth stopped Elizabeth's heart with a wave of her hand and Abaddon caused people to bleed from their eyes. Crowley was even able to cause a girl to explode by snapping his fingers.
 * Electrokinesis - Displayed by Azazel and Crowley. They could manipulate electronic equipment to their will. Also the higher demon possessing Isaac's corpse was able to switch on an old radio.
 * Invisibility - Some demons can become invisible to humans.
 * JessPyro.jpgPyrokinesis - Some demons can generate and manipulate fire. Azazel and (probably) Brady have demonstrated this ability. Crowley can also manipulate fire; he has lit a fireplace by raising his hand, extinguished a Holy Fire circle by snapping his fingers, and also pretended to set himself on fire.
 * Telepathy - Dean mentions that some demons can read minds. Envy used this ability to gain intimate knowledge about Tamara's past without ever encountering her before or possessing her.
 * Soul Reading - Some demons, particularly Crossroad Demons, can assess the condition of one's soul.
 * Spell Casting - Some demons can practice witchcraft, much like witches, like altering the range/space they occupy. Other demons are adept in Enochian magic which they use to protect themselves from Angels. Alastair knew of a spell that could allow him to banish an angel back to Heaven. Meg and Casey knew of spells that they could use while inside a Devil's Trap, allowing them to break free. Astaroth was extremely skilled in magic and used it to kill witches, almost kill Dean and severely hurt Ruby.
 * Teleportation - White-eyed Demons, Princes of Hell, Knights of Hell, Crossroad Demons, and powerful Black-eyed Demons are able to teleport from one place to another, without occupying the space in between.
 * Terrakinesis -  Some demons can create small earthquakes. This was once used to destroy a Devil's Trap drawn by Kevin Tran. Abaddon was also able to create an earthquake with her presence that broke a Devil's Trap restraining Crowley.
 * Voice Mimicry - Crowley was able to mimic his original hosts voice while possessing Mrs. Tran in order to taunt the Winchesters. Though never confirmed, it is hinted at that Ruby may have been the one that sent Sam a voice text of Dean, distorting what Dean would have really said.
 * Thermokinesis - Certain demons such as Lilith and Crowley can emit great heat through their skin resulting in severe burns to whatever they touch. Lilith used this power to scald Sam when forcefully kissing him and later to burn through a Devil's Trap. Crowley once caused Ruby's knife to burn red hot by merely snapping his fingers, forcing Dean to drop it.
 * Weather Manipulation - Some demons such as Meg and Father Gil are able to alter the weather to a limited extent such as creating sudden gusts of wind. More powerful demons like Azazel can create stronger winds and Abaddon could trigger thunder and lightning merely by screaming.
 * Regeneration - At least some demons can heal their hosts from any physical injury they sustain. Meg was able to heal several broken bones after falling from a window. Crowley, Meg and Ruby have all been shot on several occasions and show no signs of injury following the incident. Crowley has also healed his vessel after being severely burned by an angels white light and being stabbed through the shoulder by an angel blade. However, after leaving their host, any injuries the body has sustain reappear and the host dies. Oddly, while Crowley has vacated his vessel several times, many of his injuries did not reappear on his host.
 * Telekinesis - Demons can move or suspend objects and other beings with their minds. Higher ranking demons can use this ability to pin their victims to walls or kill people by snapping their necks.

High-Level Powers
Knights of Hell, Princes of Hell, White-eyed demons, Samhain and Crowley as the King of Hell are the only ones to use these powers. They also possess all the previous abilities at enhanced levels and are incredibly strong. Lilith and Alastair are known to be powerful enough to fight and even overpower most angels on the celestial chain of command. They will still flee when confronted by Archangels.
 * Advanced Biokinesis - Azazel was able to cause internal bleeding by merely looking at someone. Alastair is able to make humans grip their chests and fall down. Abaddon is able to cause permanent blindness and Asmodeus is able to choke both demons and humans with a wave of his hand.
 * Advanced Teleportation - High ranking demons such as Azazel, Alastair, and Crowley can easily teleport themselves back and forth between Earth and Hell, without the need for any complex summoning ritual or assistance. This however, varied among high-tier demons, as some were kept imprisoned due to unknown reasons and methods.
 * Animal Communication - Crowley displayed the ability to understand Olivette when she was communicating with him in the form of a hamster.
 * Dream Walking - Displayed by Azazel only on the special children. He could enter and control the dreams of his targets and Crowley in a deleted scene for Brother's Keeper on the season 10 DVD Crowley displayed this ability to visit Dean in his dreams.
 * Mental Manipulation -Displayed by Crowley only, he was able to grant his illiterate son the ability to read simply by touching his head.
 * Advanced Immunity - As a general rule, the more powerful the demon, the more resistant they are to harm and common anti-demon methods such as salt and holy water. High ranking demons like Alastair are immune to the Killing Touch of normal angels and both he and Abaddon are immune to the killing effects of the Demon-killing knife though it causes them pain. The Knights of Hell could only be killed by the First Blade and Cain, the original Knight, is completely immune to the knife to the point it doesn't even hurt him. Azazel is completely immune to holy water, and salt. He is so far the only demon shown to have immunity to those anti-demon methods. White-eyed demons,The Princes, Cain, Samhain had near-to-complete immunity to the demon-killing knife. Abaddon could only be incapacitated by it.
 * Memory Manipulation - Displayed by Crowley and Azazel. Crowley stated that he "scrubbed" Kevin's short term memory and Azazel was able to erase Dean's memory of his conversation with Tessa.
 * Memory Extraction - By inserting part of her essence into her victim, Abaddon could access their memories (even their subconscious memories) and gain information about what they had seen and heard.
 * Exorcism - Displayed by Abaddon and (possibly) Lilith. She forced a demon out of its host and back to Hell by choking its vessel. Lilith also claimed that she sent Ruby to Hell and then possessed her vessel.
 * Smiting - Cain, one of the first and the most powerful demons, displayed the power to smite other demons similar to angels, but with a red glow rather than a white one. The Prince of Hell Asmodeus was able to smite demons in an identical manner to angels just by clenching his fist.
 * Molecular Combustion - Simply by touching an angel, Dagon was able to make them combust into dust. Asmodeus was able to turn a man to dust with just a wave of his hand.
 * Sedation - Crowley was able to render an entire diner full of people unconscious in the blink of an eye.
 * Shapeshifting - The Prince of Hell Asmodeus was able to seamlessly change his shape into those of other people.
 * Photokinesis - Used by Lilith (Jus In Bello, No Rest for the Wicked), Samhain (It's the Great Pumpkin, Sam Winchester) and Asmodeus (The Rising Son). High ranking demons can use this to generate massive amounts of destructive energy that can obliterate large areas. This ability is extremely rare and are otherwise present only by angelic beings.

Special Powers
These powers can generally only be accessed in the context of a Deal or performed in Hell.
 * Healing (by deals) - In the context of a deal, crossroads demons can heal themselves and others of any wound as demonstrated by Azazel and Crowley.
 * Reality Warping (by deals) - Crossroads demons, and a few other Demons can grant humans a wish in exchange for their souls. It is worth noting that Azazel did not need to take souls, and could grant wishes from his own power, which he did in exchange for permission to enter the homes of special children, on their 6-month birthday. Lilith also claimed she could make deals without taking a soul but this was never confirmed. While in Hell, demons can alter reality to torture people in ways that are beyond human imagination. One of the reasons Alastair despises being on Earth is because reality is "too concrete" and there are too few resources for torturing people efficiently.
 * Resurrection (by deals) - One of the wishes demons can grant is the resurrection of a loved one. Crowley claims that, since he is now the King of Hell, he is strong enough to resurrect anybody in his care without a deal. Azazel also displayed resurrecting, the young John Winchester after he killed him, in the context of a deal. He couldn't however resurrect Dean and instead, he possessed a Reaper, who he used to do it for him. When Luther Shrike managed to leverage him with his bones, Barthamus was forced to resurrect him after dragging Luther's soul to Hell.
 * Shapeshifting - Demons can take any form they wish while in Hell. Several demons were able to take the appearance of Sam and Dean while torturing Bobby Singer in Hell.
 * Mind Control - The Seven Deadly Sins each possess the ability to force humans to carry out lethal actions based around the sin they represent. For example, Envy forced a woman to kill another to obtain a pair of shoes, Sloth forced a family to remain seated so they would dehydrate and starve to death and Gluttony forced Isaac to drink drain cleaner. This ability appears to be unique to the Seven Deadly Sins.
 * Summoning - Samhain was able to summon ghosts, zombies and other supernatural creatures. He is the only demon known to possess this ability.
 * Power Granting - Through deals, demons are able to turn humans into witches that harness demonic power. After Luther blackmailed him with his bones, Barthamus was forced to resurrect him and grant Luther immortality, particularly on his property where Luther couldn't be killed.

Banishing, Harming, Misleading or Trapping

 * Devil's Trap - This can bind, imprison and overpower demons.
 * Devil's Trap Bullets - A faster/more practical way to trap and overpower most demons.
 * Supernatural Handcuffs - A faster/more practical way to trap and overpower demons without harming or killing their vessel.
 * Holy water - Holy water burns most demons that come into contact with it.
 * The word "Christo" - The pronunciation of this word makes nearby demons reveal their demonic eyes.
 * Exorcism - Demons can be exorcised and sent back to Hell using many forms of this ritual.
 * Reverse Exorcism - It can prevent a demon from leaving a vessel if they try to escape torture, interrogation, etc.
 * Jim Murphy's Knife - Even a higher black-eyed demon avoided being hit by this knife, which implies that it can at least harm or maybe even kill some demons.
 * Anti-possession Sigil - It can prevent a demon from possessing someone; usually used as a tattoo by hunters.
 * Anti-Exorcism Sigil - By carving a particular sigil into a demon's possessed flesh, it is possible to lock the demon within its vessel; this can prevent a demon from escaping torture or interrogation, but also can be used by the demon to prevent themselves from being exorcised.
 * Ghosts - Ghosts can pull Demons from their vessels as shown when John Winchester's spirit grabs the powerful Prince of Hell Azazel.
 * Hallowed Ground - Low level demons are unable to enter hallowed ground.
 * Hex Bags - Hex bags can be used to hide people from demons. A variant also could harm and kill demons.
 * Holy Fire - Holy fire could destroy a demon's vessel and is capable of killing some of them.
 * Iron - Most demons are vulnerable to iron and contact with it burns their skin.
 * Palo Santo - Holy Wood that effects demons in the same way as holy water. It is capable of harming and immobilizing even higher level black-eyed demons like the Seven Deadly Sins, while also making it easier for them to be exorcised.
 * Demon Cure - A demon could become a human again by this ritual.
 * Purified Blood - Main substance for curing demons, it is also capable of harming them.
 * Salt - Most demons are unable to cross a line of salt and could be harmed and tortured by it.
 * Ingestion of Salt - Under some circumstances, the ingestion of large quantities of salt can force a demon to vacate its host.
 * Hyperbolic pulse generator - This device emits a force that can effectively exorcise a demon or an angel from their vessel.

Entities
Possessing the Mark of Cain is an exception to many of the beings that can kill Demons. It has been shown that only the first blade when used by a being marked with the Mark of Cain can kill another so marked. Even Death said he could not do so unless Dean passed on the Mark first.
 * Angels - Angels are capable of overpowering and smiting most demons. Higher ones can kill even the oldest demons. It is unknown if regular Angels can kill Knights or Princes, although this seems unlikely, as angels have been overpowered in many confrontations with them.
 * Hellhounds - Hellhounds could overpower and kill demons.
 * High-tier Demons - Stronger demons can overpower or even smite lower demons.
 * Special Children - Demons are vulnerable to a special child's powers and could be killed by them. A Special Child was able to kill the powerful White-eyed Demon Alastair.
 * Cambions - A cambion who is destined to be anti-christ, is able to immobilize, silence, exorcise and control low-level demons. It is unknown how they would fare against more powerful demons.
 * Nephilim - While empowering the Seraphim Castiel, Jack was able to grant him the power to easily overpower, render powerless and kill the Prince of Hell Dagon, one of the most powerful demons to ever live. Additionally, when Jack became angry, the Prince of Hell Asmodeus fled rather than face Jack in battle.
 * Primordial Entities - Primordial beings such as God, The Darkness, Death, and the Archangels can easily smite any demon.

Weapons, Rituals and Spells

 * Angel Blade - Angel blades are capable of killing most demons. Princes and Knights have shown to be immune to Angel Blades.
 * Burning their Human Remains - Burning a demon's original human bones is capable of killing them, causing both the demon in question and their vessel to burn to ash.
 * Death's Scythe - This scythe is capable of killing demons.
 * Demon bomb - This spell could kill demons.
 * Hand of God - The power of the Hand of God is capable of reducing a demon into dust.
 * Magic - Demons could be restrained, harmed and killed by magic.
 * Demon-Killing Knife - This knife could injure and kill most demons. Princes and Knights have shown to be immune.
 * The Colt - Since this gun can kill anything but Lucifer and other four beings in the existence, it's capable of killing demons.
 * The First Blade - The First Blade, combined with power from the Mark of Cain, is capable of killing demons.
 * Virgin Sacrifice Spell (possibly) - Ruby claimed to know a spell that would destroy any demon within a one-mile radius.
 * Lance of Michael - Angelic weapon created by the archangel Michael to slowly and painfully kill Lucifer. Will kill any demon stabbed with it causing them to explode into dust. It was able to kill the very powerful Prince of Hell Ramiel.
 * Blood Draining - Sam Winchester and Ruby were able to kill a demon by draining all of her blood for Sam to use to fuel his powers.

White-eyed Demons

 * Lilith (deceased)
 * Alastair (deceased)

Princes of Hell

 * Azazel (deceased)
 * Ramiel (deceased)
 * Dagon (deceased)
 * Asmodeus

Knights of Hell

 * Abaddon (deceased)
 * Cain (deceased)
 * Dean Winchester (cured)

Crossroad Demons

 * Dean's Crossroad Demon (deceased)
 * Bela's Crossroad Demon
 * Unnamed male (deceased)
 * Crowley (deceased)
 * Bobby's Crossroad Demon (deceased)
 * Unnamed male (deceased)
 * Guy (unknown)
 * Unnamed male (deceased)
 * Grandma (Crossroad Demon) (exorcised)
 * Snooki's Crossroad Demon (exorcised)
 * Dar (unknown)
 * Unnamed male (deceased)
 * Guthrie (deceased)
 * Duke (deceased)
 * Jael (exorcised)
 * Barthamus (deceased)

Black-eyed Demons

 * Abaddon Loyalist (deceased)
 * Abaddon's Demon Army (deceased)
 * Abaddon's Demon Guards (deceased)
 * Abaddon's Henchmen (unknown)
 * Abaddon's protégé (exorcised)
 * Alastair's Henchmen (two deceased, one exorcised, two unknown)
 * Aldo (unknown)
 * Amelia Novak demon (exorcised)
 * Asmodeus' Messenger (exorcised)
 * Asmodeus's Victims (deceased)
 * Astaroth (deceased)
 * Bar Demon (deceased)
 * Barthamus' Minion (deceased)
 * Blood Source Demons (deceased)
 * Blue Earth Demons (eight deceased)
 * Bobby Singer demon (deceased)
 * Casey  (deceased)
 * Captured Demon (deceased)
 * Captive Demon (exorcised)
 * Castiel's Captive (deceased)
 * Cecily  (deceased)
 * Channing's demon
 * Claire's captors (deceased)
 * Cole's Captive (unknown)
 * Convenience Store Demon (deceased)
 * Cop Demon (deceased)
 * Cowboy Demons (deceased)
 * Crowley's Trusted Advisors (unknown)
 * Crowley's Assassins (deceased)
 * Crowley's Captors (deceased)
 * Crowley's Lair Guards (one deceased)
 * Crowley's Mansion Guards (deceased)
 * Brady (deceased)
 * Bearded Demon (deceased)
 * Cindy McKellan's demon (deceased)
 * Christian Campbell Demon (deceased)
 * Demon Minion
 * Dean's Captives (deceased)
 * Del (deceased)
 * Demon (The Bad Seed)
 * Deputy Demon (unknown)
 * Dermott Culp (deceased)
 * Drew Neely (deceased)
 * Duane Tanner
 * Documents Holder
 * Drexel
 * Eunis (deceased)
 * Ellsworth (deceased)
 * Ellsworth's Hunters (deceased)
 * Executed Demon (deceased)
 * Executioner Demon
 * Famine's Soul Carrier (deceased)
 * Famine's Servants (exorcised)
 * Father Gil  (deceased)
 * FBI Demon (exorcised)
 * Gerald (deceased)
 * Grab (deceased)
 * Gordon's Captive (exorcised)
 * Harrington (deceased)
 * Hell Dungeon Guards (deceased)
 * Humboldt Hotel Guard (deceased)
 * Hotel Assassins (deceased)
 * Iowa Factory Guards (deceased)
 * Jackson  (deceased)
 * Jake
 * Jason (deceased)
 * Jeffrey's Demon (exorcised)
 * Julia Wright's demon (exorcised)
 * Jervis (deceased)
 * Karen Singer demon (exorcised)
 * Kevin's Demon Guards (deceased)
 * Linda's Attacker (deceased)
 * Lilith's Assassins (two deceased, one exorcised)
 * Lilith's Entourage (deceased)
 * Lucifer's Guards (deceased)
 * Lucifer Loyalists (deceased)
 * Lisa and Ben's Captors (five deceased, three alive)
 * Lisa Braeden demon (exorcised)
 * Marco (deceased)
 * Marcus (deceased)
 * Meg (deceased)
 * Meg's Captors (deceased)
 * Meg's Minion
 * Merrick
 * Messenger Demon (deceased)
 * Monster Prison Guards (deceased)
 * Mr. Richie (deceased)
 * Muffin's Owner (unknown)
 * Nebbishy Demon
 * Nebraska Factory Guards (deceased)
 * Niveus Guard (deceased)
 * Niveus Warehouse Guards (deceased)
 * Nora's demon (exorcised)
 * Old Woman demon
 * Orderly Demon
 * Pestilence's assistant (deceased)
 * Peter Kent demon (cured)
 * Pimp Demon (deceased)
 * Rachel Nave (deceased)
 * Ramiel's Female Protector (deceased)
 * Ramiel's Protector (deceased)
 * Raul (deceased)
 * Red (deceased)
 * Rodger (deceased)
 * Rodger's wife
 * Rosco (deceased)
 * Rosco's Partner (deceased)
 * Ruby (deceased)
 * Sam Winchester imposter (deceased)
 * Siege Demons (deceased)
 * Sierra (deceased)
 * Simmons (deceased)
 * Smitty (unknown)
 * Spevak (deceased)
 * Suicidal Demon (deceased)
 * Tablet Hunters (deceased)
 * Thomas (deceased)
 * Tom (deceased)
 * Trucker Demon)
 * Trish (unknown)
 * Two-Faced Demon
 * Viggo (deceased)
 * Waitress (exorcised)
 * Winchester imposters (unknown)
 * Wingman Demon (unknown)

Special Demons

 * Acheri
 * Daeva
 * Disaster Demon (exorcised)
 * Croatoan
 * Green-eyed Demons  (mentioned only)
 * Samhain (exorcised)
 * Seven Deadly Sins
 * Envy  (exorcised)
 * Gluttony  (deceased)
 * Greed (deceased)
 * Lust (exorcised)
 * Pride (deceased)
 * Sloth (exorcised)
 * Wrath (exorcised)
 * Tempter Demon

Cambion

 * Jesse Turner

Non-Canon

 * Azazel (Anime Series)
 * Agrat Bat Mahlat  (unseen; tie-in Novels only)
 * Belial  (tie-in Novels only)
 * Eisheth  (tie-in Novels only)
 * H  (tie-in Novels only)
 * Judas (tie-in Novels only)
 * Moa'ah  (tie-in Novels only)
 * Orange-eyed Demons (mentioned in Bobby Singer's Guide to Hunting)
 * The Heart of the Dragon (Demon)  (tie-in Novels only)

Appearances
As the primary antagonist of the series, Demons, along with Angels, are arguably the most recurring supernatural creatures in the series, appearing in a total of over 100 episodes.

Season 1

 * Pilot (silhouette; first appearence of a Prince of Hell)
 * Phantom Traveler (first appearence of a Disaster Demon)
 * Scarecrow (first appearence of a regular Black-eyed Demon)
 * Shadow (first appearence of a Daeva)
 * Salvation
 * Devil's Trap

Season 2

 * In My Time of Dying
 * Crossroad Blues (first appearence of a Crossroad Demon)
 * Croatoan (first appearence of the Croatoan Virus)
 * Hunted (offscreen)
 * Born Under A Bad Sign
 * All Hell Breaks Loose - Part 1 (first appearence of a Acheri)
 * All Hell Breaks Loose - Part 2

Season 3

 * The Magnificent Seven (first appearence of the Seven Deadly Sins)
 * The Kids Are Alright
 * Sin City  (first mention of a Succubi)
 * Bedtime Stories
 * Malleus Maleficarum
 * Dream A Little Dream Of Me (in a dream)
 * Jus In Bello (first appearence of a White-eyed Demon)
 * Time Is On My Side
 * No Rest For The Wicked

Season 4

 * Lazarus Rising
 * Are You There, God? It's Me, Dean Winchester
 * In The Beginning
 * Metamorphosis
 * Yellow Fever (hallucination)
 * It's the Great Pumpkin, Sam Winchester (first appearence of a Multicolor-eyed Demon)
 * I Know What You Did Last Summer
 * Heaven and Hell
 * Criss Angel Is A Douchebag
 * Sex and Violence (voice only)
 * Death Takes A Holiday
 * On The Head Of A Pin
 * The Monster at the End of This Book
 * The Rapture
 * When the Levee Breaks
 * Lucifer Rising

Season 5

 * Sympathy for the Devil
 * Good God, Y'all (hallucinations)
 * Free To Be You and Me (offscreen)
 * I Believe The Children Are Our Future (first appearence of a Cambion)
 * Abandon All Hope...
 * Swap Meat
 * My Bloody Valentine
 * 99 Problems
 * The Devil You Know
 * Two Minutes to Midnight
 * Swan Song

Season 6

 * Exile on Main Street (hallucination)
 * Weekend At Bobby's
 * Family Matters
 * All Dogs Go To Heaven
 * Caged Heat
 * Mommy Dearest
 * The Man Who Would Be King
 * Let It Bleed
 * The Man Who Knew Too Much

Season 7

 * Meet The New Boss
 * Slash Fiction
 * Season Seven, Time For A Wedding
 * Repo Man
 * The Born-Again Identity
 * Reading Is Fundamental
 * There Will Be Blood
 * Survival of the Fittest

Season 8

 * We Need To Talk About Kevin
 * What's Up, Tiger Mommy?
 * A Little Slice of Kevin
 * Torn and Frayed
 * As Time Goes By (first appearence of a Knight of Hell)
 * Goodbye Stranger
 * Taxi Driver
 * The Great Escapist
 * Clip Show
 * Sacrifice

Season 9

 * Devil May Care
 * Slumber Party
 * Heaven Can't Wait
 * Road Trip
 * First Born
 * Captives
 * Blade Runners
 * Mother's Little Helper
 * King of the Damned
 * Do You Believe In Miracles?

Season 10

 * Black
 * Reichenbach
 * Soul Survivor
 * Girls, Girls, Girls
 * The Things We Left Behind
 * The Hunter Games
 * The Executioner's Song
 * Paint it Black
 * Inside Man
 * Dark Dynasty
 * The Prisoner
 * Brother's Keeper

Season 11

 * Out of the Darkness, Into the Fire
 * Form and Void
 * The Bad Seed
 * Our Little World
 * O Brother, Where Art Thou?
 * The Devil in the Details
 * The Vessel
 * Beyond the Mat
 * Hell's Angel
 * The Chitters  (first mention of a Green-eyed Demon)
 * We Happy Few
 * Alpha and Omega

Season 12

 * Keep Calm and Carry On
 * Mamma Mia
 * The Foundry
 * Celebrating The Life Of Asa Fox
 * Rock Never Dies
 * LOTUS
 * First Blood
 * Stuck in the Middle (With You)
 * Family Feud
 * Somewhere Between Heaven and Hell
 * The British Invasion
 * The Future
 * There's Something About Mary
 * All Along the Watchtower (first appearence of a Tempter Demon)

Season 13

 * The Rising Son
 * War of the Worlds
 * The Scorpion and The Frog

Trivia

 * The first demon ever to appear (a disaster demon in Phantom Traveler) was notably different from the other demons that would later appear. This was the result of several retcons by the writer as they developed the demon lore.
 * Demons' true forms are almost never seen on Supernatural, but if one looks carefully in All Hell Breaks Loose - Part 2 after John pulls Azazel out of his vessel, a decaying skull-like face is visible within Azazel's smoke form. This is arguably also seen in demons stabbed with the demon knife or an angel blade, when their vessels flash orange and the skeleton beneath is visible.
 * Crowley's true form took on a reddish smoke, as opposed to the usual black color.
 * In Bobby Singer's Guide to Hunting, Samhain was described as a blue-eyed demon (which is partly true, since his irises are very light blue).
 * It also states that orange-eyed demons exist and that the white-eyed demons aren't extinct and implied that they are immune to exorcism.
 * Demons are the main antagonists of the show, and the most recurring one. Up to date four main villains have been demons, specifically Azazel, Lilith, Crowley and Abaddon. Likewise three secondary villains have also been demons, specifically Meg, Alastair and Ruby.
 * In Frontierland, Samuel Colt kills two demons who, upon death, flash blue opposed to the regular red-orange. It is never explained how the demons differed from others. Azazel's demonic son, Tom, also shared this trait when he was killed by the Colt.
 * In Taxi Driver, it is implied that demons do not need vessels to appear human while in Hell, as one on-screen demon (and many more off-screen) were able to appear as Sam Winchester without possessing him.
 * It appears that the King of Hell can turn demons to dust with just a snap of his fingers, as Crowley did to an unnamed demon. Whether this destroys the demon or merely banishes it back to Hell is unknown.
 * In the episode The Chitters, it has been revealed that Green-eyed Demons exist.
 * Samhain and Ramiel are the only high-tier demons that appeared in just one episode.
 * It has been shown on several occasions that most, if not all, monsters too are aware of the existence of demons; while the vast majority seem to fear demons greatly, the higher-tier monsters apparently do not.
 * Unlike humans and angels, no demon has ever been resurrected, making it unknown as to whether this is possible. Azazel was seemingly resurrected at the beginning of Season 6, but this was just an illusion created by a Djinn.