Lesser Evils

The Lesser Evils are powerful demon lords with less power than Diablo, Mephisto and Baal (called the Prime Evils).

All Lesser Evils

• Andariel, Maiden of Anguish (prominent daughter of Lilith)
• Azmodan, Lord of Sin
• Belial, Lord of Lies
• Duriel, Lord of Pain (also known as Prince of Pain)

Lilith, Mother of Misery, Queen of the Succubi and mother to Andariel is not normally counted among the seven great evils, but is just as powerful.

Background

The Lesser Evils have have ruled their domains in the Burning Hells for eons, and fighting among themselves for power within their own ranks. These four Lesser Evils wanted the power of the three Prime Evils.

When the Nephalem were born in ages past, The Three focused on securing allegiance of this new power to turn the tide in the war between demons and angels. In this time, many demons were annoyed that the war with the High Heavens had been put to a halt and the Lesser Evils, lead by Azmodan and Belial took the chance of overthrowing the three in what is called the Dark Exile.

This was in fact just a manipulated set of circumstances by the Three, but not something they knew about. Unexpectedly by the Prime Evils, they were captured by the Horadrim. Internal struggles inhibited the Lesser Evils from launching their crusade against the High Heavens.

When Mephisto and Diablo were freed, some sort of new revolution happened in hell, as the Three retook the control of at least Andariel and Duriel, who were punished by their revolt by guarding the path East from any force trying to stop the Dark Wanderer from releasing Baal and reaching Kurast.

It's unknown what politics in Hell have gone on in the 20 years since the Three were once again defeated, but most likely, the Lesser Evils are once more forced in line under the Prime Three.

In-Game References

Only Azmodan and Belial out of the seven greater evils have not been presented in any Diablo game. Diablo I only features Diablo himself, and Diablo II with expansion shows all five, bar those two. Even Lilith appears in the game, in the Pandemonium Event, where the heroes creates a portal to her realm (but her actual presence on Sanctuary is not really confirmed as canon lore).

Reference

• Sin War Trilogy
• Pandemonium Event