Azzael was worshipped as a god in Babylon. He was later worshipped by witches in Lancashire, Abbotsbury, East Bromwich, and Faversham.
Azzael consorted with the English witch Sarah Hughes and granted her powers in 1574. In 1617, Hughes renounced the sins of her youth upon her deathbed. Her body was chained in her coffin in a church in East Bromwich and watched over by her human children, a priest and a nun. If they could keep her for three nights, Azzael's claim over her would be broken.
When Azzael came on the first night, he incinerated her children. He took his bride, telling her that she was carrying his child, whom he referred to as "a son, my favorite son." Azzael threaded Sarah Hughes on one of the hooks hanging from his horse and rode off to Hell.
Sarah Hughes died giving birth to the child who would eventually be called Hellboy. Shortly after his birth, Azzael cut off the infant's right hand and grafted the Right Hand of Doom in its place. When the nobility of Hell learned what he had done, they sent angels of destruction to his palace. But they arrived too late. Azzael's newborn son had already been sent away, and so Azzael was stripped of his title and frozen in ice.
On May 14, 1994, Hellboy returned to East Bromwich where he had a vision of the events which transpired in 1617, with Azzael staring directly at Hellboy while claiming Sarah Hughes. Hellboy would later learn of Azzael's identity as his father.
While in Hell, Hellboy had the chance to claim his father's possessions, of which there were three; a sword, his throne, and a ring with a fly trapped inside it. He declined. He also did battle with his half-brothers Gamon and Lusk, the former of whom made the mistake of calling their father a fool. For this disrespect, Gamon was beheaded by his uncle, Astaroth.
Azzael's name and character is likely inspired by Azazel, a fallen angel from the Book of Enoch, who is also often appears as a demon who introduced humans to forbidden knowledge and magic, securing several women.
- In the 2008 film Hellboy II: The Golden Army, Nuala refers to Hellboy as "Son of the Fallen One" confirming his royal right to challenge for command of the Golden Army; as anyone of noble birth and titles can claim control with the Crown of Bethmora.