Demonology A-B-C

Abraxas
Ardo Malorum
Alchemists
Andras
Anton
Arnon
Bacarra
Banshee
Barbas
Belthazor
Bosk

Bounty Hunters
Brotherhood of the Thorn
Brute Demons
Chameleon Demons
Collectors
The Council
Creeper Demons
The Crone
Cronyn & Doris
Cryto

Abraxas
A demon from the astral plane. He vanquishes witches by demonizing their powers: first her transfers the witch's Book of Shadows to a parallel plane, and then read it backwards, undoing the magic they've done, the demons they've vanquished, etc. Until he reaches the first page of the Book, removes the witch's powers and obtains them for himself.
Ardo Malorum
These generals commanded the demonic legions, leading the war against the forces of good. To ascend in the unholy hierarchy they must capture and conquer those witches who protect the innocent and value good. The servants of these generals are known as level two demons, and can be recognized by the weapons they carry.
 
Alchemists
Alchemists can bring the dead back to life. Not only that, they also have to ability to transform really anything, like water into gold.

Alchemist's Tools

Essence Bearer
A bottle used to capture and/or store Life Essence. Life Essence can possess any living being, but it is poisonous in therefor will inevitably prove lethal to the being's host soul. If the alchemist adds his own blood to the essence, it will share his powers.

Crimson Scalpel
This ceremonial instrument is used by an Alchemist to open an incision in a body. The demon then performs an incantation on the blood and lets it drip into the Essence Bearer, where it is mixed with other ingredients and transformed into a life essence.

Blazing Alembic
This transforms matter into energy. First, the alchemist puts matter in this device, then heats it over a ritualistic flame. After invoking the dark spirit, the matter distills into energy, which can be manipulated for evil purposes.

Mutator
This contraption transforms one type of matter into another. The alchemist puts the initial sudstances inside the first cylinder. Then, while he chants, the substance materializes in the second cylinder in an completely different form.
 
Andras
The Spirit of Rage. He uses anger to engrage his victims, until the do an act of violence. After the act is done, the rage leaves the victim, but the violence usually serves a greater purpose, making Andras more powerful.
Andras is known of using his powers to enrage people, followed by wars, that even lasted for decades.
Anton
An immortal warlock from the 1920s, who has to power to glamour. He fell in love with a Warren witch; P. Russell, who happens to be one of Phoebe's past lifes. He seduced her into turning evil and help him get her cousin's powers. However, her cousins found out about this and killed their cousin, after cursing her so she and Anton would never join forces in any lifetime again.
Arnon
A lower level demon with the ability of sensing. He uses this ability to sense great and powerful magical beings, who can help him to gain great power. He also has the power of strangulation.
Bacarra
A warlock who's attempt was to rule the underworld. Therefore, he travelled back to the past and teamed up with his past self, using his future knowledge to steal and get control of the Halliwell's Book of Shadows, so he would have enough power to take over the underworld.
Banshee
As a former witch, a Banshee seeks those who are in great pain, and feed of their pain, causing them to eventually die. Anyone who hears the scream of the Banshee, suffers death, but those who are witches, are turned into a Banshee themselves. Only a dog can hear a Banshee's scream from far distances.
Barbas
The demon of fear. Every thirteen hundred years on friday the 13th he goes to earth to kill thirtheen unmarried witches in order for him to break free out of his prison in the underworld. He kills the witches by reading their worst fears and turning them into reality, literally scaring them to death.
While he was in Purgatory, Barbas gained the ability to astral project. He used this to plant thoughts in Cole's head, making him afraid of his new powers, eventually convincing him to strip himself of this powers so Barbas could absorb him. This allowed Barbas to emerge from Purgatory permanently.
Belthazor
The Source's right hand. As an upper level demon, he was part demon part human. His human part was named Cole Turner. He lived over a century, torturing and killing countless innocent witches. For as far as we know, he has the ability to throw energyballs and shimmer from place to place. However, these may not be his only powers.
Belthazor is very intelligent and not to be trusted. Because he has a human side, he understands humans better than other demons, which makes him even more dangerous.
Bosk
A low level demon who attacks his victims by shooting light darts at them. Bosk planned to resurrect the lost city of Zanbar, a city of magic. With his army of fourty thieves he searched in the desert for his former site. He planned on using his Genie Jinny to wish it back after finding it, but he failed.
Bounty Hunters
Heartless, low level demons who will do really anything to get their bounty. Usually they track down fugitive demons, but if they got offered a right price, they will hunt down and kill anyone to get their bounty. They have to power to throw energyballs and/or lightening bolts and can materialize at will.
 
Brotherhood of the Thorn
A very exclusive niche of the demon community. The members of the Brotherhood are handpicked by The Source himself. They have to take a blood oath upon admittance.
Brute Demons
Upper level demons, with overwhelming physiscal strenght. They work alone and usually kill by crushing their victim's skull.
Chameleon Demons
Chameleon demons are shapeshifters, and therefore allowed to turn into any object they wish. This makes them very useful at gaining information without being detected.
Besides shapeshifting, Chameleon demons also have the ability regenerate their extremities and they have the ability to teleport, by shimmering.
Collectors
Creepy warlocks with needle-like fingers, which they can insert in people's brains allowing them to quickly gain information. After this happens, the victims will lose part of their memory and become catatonic. Collector also can put the information back in someone's head, which revives the person.
A collector's greatest weakness is his thirst for knowledge.
The Council
A high ranking group of demons who are responsible for organizing attacks on specific induviduals. Usually they assign lower level demons to do the job for them.
 
Creeper Demons
Creeper demons cloak themselves in the shadows and prey upon spirits. Vanquishing a leader of these demons vanquishes his entire clan.
The Crone
A well known and respected advisor of evil. She can forsee the future, which makes her valuable. Heard of more than some, she's an upper level demon and possesses upper level demonic powers. So an upper level demonic vanquishing spell will kill her.
Cronyn & Doris
A sorcerer. He learned of a prophecy from his mentor that one day a twice-blessed child would be born on a special day, when all magic (for one day) would cease to exist in the world. When he realized Piper was the one carrying the baby, with the help of a female demon called Doris (who became wife of Piper's dad Victor) he managed to isolate Piper while she was in labor, hoping that he could steal the child after birth and raising him or her to be a powerful force for evil.
Cryto
The demon of vanity. He lived in the 16th century, travelling from dukedom to dukedom, preying on people's vanity and bestowing youth and beauty in exchange for their souls. Cryto was found and skinned alive by a group of witches, who believed it would keep his spirit from ever being resurrected again.