Azazel is a Greater Demon and is referred to as the Forger of Weapons, and a Lieutenant of Hell, ranked second only to Lucifer himself. Azazel was among the angels who were followers of Lucifer and banished out of Heaven for their insurgence. He and Magnus' father, among others, became Princes of Hell.
Azazel is bound to the rocks of Duduael. If summoned, only his spirit will come, as his corporeal form will remain bound to the rocks of Duduael.
Azazel is credited as the corrupter of humans—the angel who taught humanity how to make weapons, knowledge previously known only among angels. This was seen as a great transgression that led to the corruption of the world, the creation of war, and, eventually, his fall. He has since been seen as the demon who was ironically responsible for giving humanity the knowledge necessary to fight against demons.
Magnus summoned Azazel for "Team Good" in New York, hoping to ask the "Forger of Weapons" about a hypothetical weapon that could possibly break the demonic parabatai bond between Jace Herondale and Sebastian Morgenstern. Azazel told them that no weapon he could create could harm one and save the other, but told them he had an idea, which he would only share in exchange for a happy memory from each person present during his summoning.
Upon receiving their memories, Azazel told them his plan, saying that after they release him into the world, he would take Jace into Hell and keep him alive long enough until their connection breaks. However, Azazel would have remained free. Horrified at the idea, Magnus banished him, telling him that they will consider his offer. Not wanting to free the Greater Demon, Magnus and the others decided to not accept it.
However, because of his sheer strength, Azazel was not entirely banished. He remained connected to the pentagram in Magnus' apartment, sending them messages through "mini-tornadoes". When Magnus' cat almost strayed into the pentagram, Simon Lewis went after it, putting him inside the demon's reach. Azazel then reappeared with Simon and attempted to harm him, only to be rebounded with pain from the Mark of Cain. Azazel wondered why the Mark was on someone as young as him, why it was placed on him, and who did it. He warned them that they were playing a dangerous game and was "bending the will of Heaven." Shocked at the choices they have been making, Azazel then left of his own accord, deciding that even his freedom was not worth gambling for them.
Azazel is a tall man with auburn hair. He has an ageless face, that seems cold and inhuman, with broad shoulders. When Magnus summoned him, he was wearing a well cut black suit with shining black shoes. His eyes were pitted and small, with leaping red flames. On his arms were the marks from a material that seemed to be cut into his skin over many decades. His skin had cracks, and both his teeth and nails were tipped with sharp needles of iron.
Azazel is a sly creature with a temper that should be feared, but likes to bring up the topic of Magnus' father frequently even though Magnus tells him not to. Azazel has also been bound for so long that he almost begs Magnus to release him.
- Religiously, Azazel is an evil spirit of the wilderness to which a scapegoat was sent by the ancient Hebrews in a ritual of atonement known as Yom Kippur. In some traditions of Judaism, Christianity, and Islam, Azazel was indeed the name of a fallen angel or demon.