Azazel, also known as Hazazel or Azael, is one of the chief governors of the Grigori, a group of fallen angels who married with female humans and in the process produced the Nephilim and a fallen member of the Watchers. Aside from Samyaza, he is the most infamous of the fallen Watchers and is the biological father of Hellboy.
Scapegoat of Humanity
In the beginning, Azazel was said to be an eater of sins. He sat up on a hill and the villages would give over their sins with a goat and send that goat into the wilderness. Azazel would then devour the goat and the sins along with it. However, the more sins that Azazel devoured, the more his hunger grew. Azazel was no longer content with the sins he received. He was spotted around the edges of villages, whispering into the ears of mortals. As the Watchers began to lust for the mortal women, Azazel like his brethren began encouraging people to do even greater misdeeds, and people indulged, overindulged, even. And no one knew when to stop.
Corrupter of Man
Azazel was cast out of Heaven after he taught men how to make swords, knives, shields and breastplates; and made known to them the metals of the earth and the art of working them; and all kinds of costly stones and all coloring tinctures. Because of this, the humans became corrupted and viewed themselves as invincible with such tools. The corruption brought on by Azazel and the Grigori degrades the human race, and the four archangels being Michael, Gabriel, Raphael, and Uriel were stated to have witnessed much blood being shed upon the earth and all lawlessness being wrought upon the earth.
The humans even went so far as to demand the angels above to have an audience with God, and to raid Heaven itself in order to learn the secrets of Paradise and the ones that God holds. When God saw what Azazel's actions have wrought he told Raphael to bind Azazel's hand and foot and cast him into the darkness: and make an opening in the desert and toss him therein. He would then place upon him rough and jagged rocks, and cover him with darkness, and let him abide there forever, and cover his face that he may not see light.
Imprisonment and Hellboy
Azazel remained in his prison for so long that the jagged rocks of Dudael apparently tore his physical body away. He became a writhing mass of darkness covered in mouths and eyes. Azazel and the Watchers would eventually be freed by Lucifer and would join the demons in Pandemonium and Hell, where he would become a Prince of Sheol and eventually the master of the witches in Longshire and Abbotsbury.
He and an English witch named Sarah Hughes, created a cambion named Anung un Rama, who was destined to release the Ogdru Jahad from the Outerverse. with the Right Hand of Doom, which was given to him by Mammon. This caused outrage in Hell, and Azazel was cast back into darkness. His son would be raised by the demon Astaroth and Aim, until he was summoned to Earth by Project Ragna Rok. During Judgement Day, it is said that those who followed Azazel's ways by misusing the purpose of weapons such as swords, will be cast into a lake of fire alongside Azazel himself.