Azmodan

Azmodan, or the Lord of Sin is one of the Lesser Evils who took over the Burning Hells along with Belial, after the imprisonment of the Prime Evils. Not much is known about him.

A civil war has been raging between the Prime Evils and Lesser Evils for quite sometime.

History

Belial, the Lord of Lies, is known to play an operational role in Diablo III, namely in Act II. Azmodan is also featured in Diablo III but his role is known to a much lesser degree than that of Belial. Belial is known to play a role of deception in Act II which ties in nicely in a thematic sense to the fact that he is the Lord of Lies. However, Azmodan is the Lord of Sin which is much more ambiguous in conception and function. It is likely that any area of the game dealing with his plot will be tailored to the theme of sin, perhaps even nodding to the Thousand Pounder who is "Gluttony Incarnate" which, gluttony in Christian mythology, is one of the seven cardinal sins (along with wrath, greed, sloth, pride, lust, and envy).

Belial and Azmodan seem to have a special relationship, as any mention of one usually invokes the mention of the other. They are both lesser evils, but when speaking of the civil war in the Burning Hells, Duriel (the Lord of Pain) and Andariel (the Maiden of Anguish) are never mentioned.

Belial and Azmodan in the Diablo I Manual

Azmodan is featured alongside Belial in the Diablo I Manual when the civil war between the lesser and prime evils is explained:

In their ignorance, the Lesser Evils began to believe that the Three were afraid to continue the war with Heaven. Frustrated by the cessation of the war, Azmodan and Belial saw the situation as their chance to overthrow the Prime Evils and take control of Hell for themselves. The two demon lords made a pact with their minor brethren, assuring them that the wretched plague of humanity would not deter the ultimate victory of the sons of Hell. Azmodan and Belial devised a plan to end the stalemate, achieve victory in the Sin War and ultimately ride the bloody crest of the Great Conflict straight into the very arms of Armageddon. Thus, a great revolution was set into motion as all of Hell went to war against the Three Brothers...

The Brothers fought with all of the savagery of the Underworld, and to their credit, annihilated a third of Hell’s treacherous legions. In the end, however, they were overcome by the Horned Death led by the traitors Azmodan and Belial. The Prime Evils, weakened and bodiless, were banished to the mortal realm where Azmodan hoped that they would remain trapped forever. Azmodan believed that with the Three set loose upon humanity, the Angels would be forced to turn their focus upon on the mortal plane - thus leaving the Gates of Heaven abandoned and defenseless. Those few demons who still pledged allegiance to the Three Brothers fled the wrath of Azmodan and Belial, escaping to the realm of Man to seek out their lost Masters.

As the warfires died out upon the battlefields of Hell, Azmodan and Belial began to argue over which of them held the higher authority. The pact that they had made quickly fell to ashes as the two demon lords took up arms against each other. The legions of Hell that remained were polarized behind either warlord, launching themselves into a bloody civil war that has lasted to this day...

Unknown monster concept art, often speculated to represent Belial or Azmodan.