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, the Demon invades their muscles, bones and brains and can also access their host's memories while possessing them (even if it is a brief possession). 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 preferences 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.
Immortality - Demons have an indefinitely long lifespan and an arrested aging process. They are also immune to diseases. Likewise, their vessels will never die nor age while possessed.
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 may simply find another human to possess, leaving their former vessel to die.
A demon throws Sam backwards with ease.
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.
Super Strength - Demons possess superior physical strength much superior to humans ; capable of physically overpowering them. Demons can also overpower most monsters. Once, a demon ripped open an airplane hatch with over 2 tons of pressure at over 1,000 feet above the ground easily.[1] Even lower demons can overpower hives of vampires and even killed a wendigo without the use of fire. 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.
Astral 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 Higgins' 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.
Brady kills Jessica with pyrokinesis.
Pyrokinesis - 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.[2]
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.
Lilith uses her White Light to obliterate the police station.
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.
Clairsentience - The Prince of Hell Asmodeus was able to sense Lucifer's return. He also believed he could detect Jack's presence, however, since Jack was cloaked, he could not.
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.
Mental Manipulation - Displayed by Crowley only, he was able to grant his illiterate son the ability to read simply by touching his head.
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.[3]
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 HellAsmodeus 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.
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 - Besides Asmodeus, weaker 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.
Procreation - Through unknown means, Julia Wright's demon was able to impregnate a human. It's unknown why this act was never repeated.
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.[4]
Hallowed Ground - Low level demons are unable to enter hallowed ground.[5]
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.[6]
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.[7]
Hyperbolic pulse generator - This device emits a force that can effectively exorcise a demon or an angel from their vessel.
Enochian Puzzle Box - A puzzle box capable of trapping a demon within in the demon's smoke form.
Special Weaknesses
Some peculiar demons have weaknesses different than those seen in any other demon.
Partial Blindness (Samhain) - Unusually for a demon, specially a high-tier one like Samhain, his eyesight is impaired, causing him to see the world blurred.
Postpartum Stress (Julia Wright's demon) - After giving birth to Jesse Turner, when the demon was weakened and tired due to the stress and pain of childbirth, this demon "passed out", his possession over Julia Wright was weakened and Julia could briefly control her body again and expel the demon by ingesting salt.
Killing
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.
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.
Angel Blades - Angel blades are capable of killing most demons. Princes have shown to be immune to Angel Blades. It is unknown if they can harm the Knights.
Angel-killing bullets - Bullets forged from melted-down angel blades are capable of killing demons.
Archangel Blades - Archangel blades are capable of killing regular demons even in the hands of regular humans.
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.
Blood Draining - Sam and Ruby were able to kill a demon by draining all of her blood for Sam to use to fuel his powers. While under Famine's influence, Sam drained and drank the blood of two demons because of his thirst for demon blood, killing them in the process.
Hand of God - The power of the Hand of God is capable of reducing a demon into dust.
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 including the Princes of Hell.
