Great Evils

"Seven is the number of the powers of Hell, and seven is the number of the Great Evils."

- Vischar Orous

The Great Evils (a.k.a. Greater Evils) are the seven most powerful demon lords of Hell. They are sub-divided into the three Prime Evils (comprised of Diablo, Mephisto, and Baal), and the four Lesser Evils (encompassing Andariel, Duriel, Belial, and Azmodan).

History
"It is with some reluctance that I write on the seven Lords of Hell, for they are the greatest of the demons, and even whispering their names seems to poison the air around me."

- Deckard Cain

Early History
"Seven Evils spawned from seven heads. Seven realms birthed from death. Infested, unending, cycles upon cycles."

- Adria

The Great Evils were formed from the seven heads of Tathamet. The three most powerful of them were spawned from Tathamet's dominant heads, and became known as the Prime Evils, holding the balance of power within Hell. The weaker four became known as the Lesser Evils. Each one of them ruled over their own domain in Hell. They led their legions against the forces of Heaven in the Eternal Conflict, while also waging wars against each other, destroying entire realms in the process.

The Eternal Conflict ground to a halt with the disappearance of the Worldstone. Because of the actions of Jere Harash however, the Prime Evils were alerted to the existence of Sanctuary, and humanity, which dwelt upon it. The Prime Evils sought to turn humanity to their own ends, to use as pawns against the forces of Heaven, instigating the Sin War. However, the Primes kept the existence of Sanctuary and humanity secret from the Lesser Evils.

The Dark Exile
"How dare you question! How dare you deny yourselves victory! Long have the Primes lorded over us. Long have they thought themselves our betters. Diablo...Diablo will fall, as will the rest. Do not be swayed or led to fear by him. Do not, for each of you will reign. Each of you will share the power we will earn."

- Belial addressing Duriel and Andariel

The Sin War ended with a truth brokered between Heaven and Hell, but the events had caused a wedge between the Prime and Lesser Evils. The Primes turned their attention to the perversion of human souls, for they realized that mankind was key to their eventual victory over Heaven. This deviation from the norm caused many of the Lesser Evils to question the authority of the Three, and so brought about a great rift between the Prime Evils and their servitors. That the Primes had not revealed the existence of Sanctuary to the Lesser Evils when they first discovered it prior to the Sin War had already soured relations between them and their lesser brothers, and Deckard Cain would speculate hundreds of years later that this deception added to the Lessers' decision to rebel.

A civil war erupted in Hell between the Prime and Lesser Evils, ending in the Lesser Evils' victory, and the banishment of the Primes to Sanctuary in what would be called the Dark Exile. As the fires of war died down, however, 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 second civil war.

Reunification
By the Darkening of Tristram, the Great Evils were still sundered&mdash;the Primes sealed on Sanctuary, while the civil war between Azmodan and Belial continued to rage. However, Diablo escaped his prison from beneath the Tristram Cathedral by possessing Aidan, intent on reuniting with his brothers. Andariel and Duriel concluded that the Primes would inevitably reclaim their position in Hell. Therefore, they endeavored to gain favor with the Lord of Terror by protecting his human host. However, over the sequence of events, five of the seven Evils were slain by a group of heroes, and furthermore, the spirits of the Primes banished to the Black Abyss, leaving Azmodan and Belial the last remaining Great Evils.

However, this was not the end, as over the next two decades, Adria enacted Diablo's master plan. The essences of the Great Evils sans Azmodan and Belial lingered on Sanctuary, and over the years, Adria marked the essences of Baal, Mephisto, Duriel, and Andariel. As such, upon the moment of its completion, the essences of five of the Evils were drawn into the Black Soulstone, and upon their respective defeats in Sanctuary, Belial and Azmodan as well. The plan Adria presented to her allies was that they could destroy all the Evils by destroying the stone once it had their essences. In truth, she was simply enacting Diablo's plan.

Leah, spawned of a union between Diablo and Adria, became Diablo's new vessel. All essences of the Great Evils were drawn into him, making Diablo a singular Prime Evil. Tathamet reborn.

Dispersal
Diablo was ultimately defeated by the Nephalem, and all seven of the Great Evils were drawn back into the Black Soulstone. However, the stone was taken by Malthael, and in battle with the Nephalem, shattered the stone before drawing the essences of the Evils into himself. After his defeat, Malthael's body disintegrated, Diablo was released, still containing the essences of the other Evils. Eventually however, each of the Evils broke away from Diablo.

Prime Evils
The Prime Evils comprise the Three Brothers - the de facto rulers of Hell:

Lesser Evils
The Lesser Evils are second only to the Three Brothers in terms of power and prestige but are nonetheless beneath them: