- Satan/Devil
Lucifer, also known as the Devil, and Satan, or the Morning Star is the former ruler of Hell and father of all demons. As the second Archangel, he is the younger brother of Michael and the older brother of Raphael and Gabriel. According to Gabriel, he was God's favorite celestial, but when God asked for all angels to bow down to humanity, Lucifer refused. He waged war against God, but was banished to Hell by Michael. All of Azazel's actions were motivated with the goal of eventually releasing Lucifer.

As an angel, Lucifer must have the permission of one to serve as his vessel, as he cannot forcefully possess a person. Being an archangel, Lucifer boasts much more power than any normal angel and also every demon.

He was finally freed and allowed to roam the Earth when the final seal (the death of Lilith) was broken by Sam. Freed from his cage, he took action to bring about the Apocalypse and cleanse the Earth (aka "The last perfect handiwork of God") of human beings (the flawed creation). Even after Lucifer was able to possess his true vessel, Sam's love for his brother Dean allowed Sam to regain control of his body, and seal himself, Lucifer, Michael, and Adam Milligan in Lucifer's Cage.

- Black-Eyed Demon
The most common demons on the show, black-eyed demons possess little to no power, whether it be super-strength or telekinesis. Effective defenses against these demons include holy water, salt, iron, a devil's trap, etc. Stronger black-eyed demons, such as Meg Masters, 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.

- Crossed Demon
Crossroad Demons have red eyes and are shown bargaining with desperate people. 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...

- Elite Demon
Only appearing at Lucifer's side in "Swan Song", these two demons were extremely strong.

- Yellow-Eyed Demon
Azazel is the only yellow-eyed demon in existence (thus far) and is incredibly powerful. Besides having a unique durability threshold, advanced telekinesis, he can manipulate fire, control dreams, make electrical devices go haywire, and can even possess Reapers. The leader of the demon army, Azazel is subordinate only to Lucifer. He is impervious to Holy Water and other conventional defenses against demons.

- White-Eyed Demon:
The most powerful class of demons, white-eyed demons possess numerous powers, the most deadly of which being white light emanation. They are highly dangerous and they rank very highly in the hierarchy of Hell, just under Lucifer. The only known demons of this type are Lilith and Alastair.