Demons

Demons are a race of malevolent supernatural beings created by the First of the Fallen. They live in the realm of Hell, which is below the mortal plane.

Demons frequently cross over to the mortal plane, using human bodies as hosts, though they can be condemned back to Hell through an exorcism. According to John Constantine, there are millions of demons. According to Furcifer, damned human souls within Hell can be transformed into demons.

Another form of demon, Time Wraiths, also reside within the Speed Force and hunt down and kill any speedster recklessly attempting to alter time. Time Wraiths can also transform said speedsters into demonic creatures driven by feral instinct and devoid of sanity, condemned to serve the will of the Speed Force for eternity as punishment for their crimes.

Powers
As supernatural creatures from Hell, demons possess a variety of powers which force vary in function of the demon.
 * Possession: Demons can possess human bodies and use them as hosts while also manifest their supernatural powers through them.
 * Accelerated healing factor: Demons are capable of rapid cellular regeneration of their host bodies, as seen when Pazuzu healed John Constantine's injuries while possessing him.
 * Electromagnetic interference: The presence of a demon cause electric systems to go rogue.
 * Electrokinesis: Furcifer can control electricity.
 * Immortality: Demons do not age, get tired, don't require food, air, or water; and can potentially live forever unless they are killed.
 * Superhuman strength: Demons are supernaturally strong. For example, the demon Lamashtu was able to hold John Constantine down into a fountain.
 * Superhuman Speed: Demons can move at superhuman speed. Lamashtu was able to instantly appear behind Anne Marie.
 * Shapeshifting/Ilusion casting: Demons can take on the appearance of other people or cast illusions that make themselves look like another person.
 * Telekinesis: Demons have the ability to move objects with their minds.

Weaknesses

 * Magic: Magic can be use to perform rituals that can defeat demons.
 * Exorcism: An exorcism well performed can force a demon to leave his host.
 * Salt: Salt acts as a shield against demons.
 * Eye of Horus: Demons can be prevented from crossing a place marked with this Egyptian symbol.
 * High-tier demons: More powerful demons can defeat another one, as proven when Constantine summoned Nergal to exorcise another demon.
 * Frequency attacks: Some demons, specifically Time Wraiths, can be destroyed if exposed to a high-enough frequency, as demonstrated by Hartley Rathaway.

Known demons

 * Durgia (mentioned only)
 * Furcifer
 * Invunche
 * Karabasan (deceased)
 * Lamashtu
 * Lilith (mentioned only)
 * Mallus
 * Mnemoth (deceased)
 * Naamah (mentioned only)
 * Nahash
 * Nergal
 * Pazuzu
 * Time Wraiths
 * Black Flash