Demons (Supernatural)

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

They are most common antagonists of the Supernatural Show aside monsters, which includes Azazel.

Physical appearance
Demons' true forms when not possessing humans are almost never seen. In All Hell Breaks Loose - Part 2, however, after John's ghost 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. From this statement, it can be assumed that demons' true form, in fact, a skeleton that engulfed by smoke.

Black-Eyed Demons
The most common and standard class of demons on the show, black-eyed demons possess only basic powers, such as 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, are not barred in entering hallowed ground and one demon, Tammi, 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. Tammi 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.

Crossroad Demons
Crossroad demons have red eyes. Unlike normal demons that serve the King of Hell, Crossroad Demons tend to be more self-serving, often bargaining with desperate people, making deals in exchange for their souls after a certain amount of time (usually ten years). They can grant wishes, collect souls, teleport, and be summoned by digging a hole in the center of a crossroads and burying a box with a picture of the summoner, some graveyard dirt, and a bone from a black cat. Gifted with immense power, these demons usually possess attractive women to lure men into making deals, although there are exceptions.

White-Eyed Demon
White-eyed demons are considered the generals of demons. They're terrifyingly powerful and they rank the highest in the hierarchy of Hell just under Lucifer himself. They inspired fear in their subordinates as all other demons seemed 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 the former of which was the very first demon to be created.

Yellow-Eyed Demon
Azazel is the only yellow-eyed demon to appear in any episode thus far. Besides having a unique durability threshold, advanced telekinesis, he 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.

Knights of Hell
Knights of Hell are very powerful demons that were handpicked by Lucifer himself and created/trained by Cain, the Father of Murder. They are some of the first fallen demons. Legend among Men of Letters had it that archangels have destroyed all but at least one but in truth Cain himself killed them. They possess a number of abilities not seen from other types of demons. They are also nearly invulnerable, being immune to exorcism rites and even the demon-killing knife. The only weapon that can kill one is The First Blade. With Abaddon's death, Cain is the only Knight of Hell remaining.

Cambions
Cambions are a demon race that are half demon but are also half human, they are created when a demon reproduces with a human, via their vessel. Jesse Turner is the only known Cambion. Their power grows when Lucifer is out of his cage.