According to the apocryphal Book of Enoch, Azazel was a leader of the grigori (also known as "watchers"), a group of fallen angels who mated with mortal women, giving rise to a race of giants known as the Nephilim. Azazel is particularly noteworthy among the grigori because it was he who taught men how to make weapons of war as well as teaching women how to make and wear cosmetics. Eventually, Azazel's teachings created such iniquity that God decided to destroy all life on Earth with a great flood (The Deluge). According to the story, God spared only Noah, Noah's family, and seven animals each of every species then in existence. They escaped destruction by living for one year on an ark that God had instructed Noah to build.
"Azazel" is found in the Bible in Leviticus 16:8, 10, and 26, but is not listed as an entity or spirit. The word is translated "scapegoat" and simply means "the goat of removal." The scapegoat is sent to wander in the desert in conjunction with another goat which is sacrificed to God, the "azazel" is led out into the desert and set free as proof that there is no longer any unexpiated guilt in the community.
Azazel is also the name given to a body-hopping demon spirit in the film, "Fallen", and the main antagonist opposite of Denzel Washington's character.
A character named Azazel also makes an appearance in the DC Comics/Vertigo series The Sandman, written by Neil Gaiman.
Azazel is also the name of an unrelated main character in the Isaac Asimov series of short stories by that name. He is a small supernatural being who meddles in the affairs of humans.
Azazel is also the main focus of the Sky One series, HEX. He attempts to seduce and mate with a woman of a certain bloodline who, if she bears his child, will release all of the Nephilim from their imprisonment in limbo.