Evil Deities

Evil Deities or Demon Gods are legendary figures in the New World, who appeared two hundred years earlier before the start of the Overlord series. Evil Deities spread chaos and destruction throughout the land until they were all eventually defeated by the Thirteen Heroes.

Background
Not much is known about what the Evil Deities were, or their number. They were estimated to be immensely powerful by New World's standards. Evil Deities only desire, as far as anyone knew, was to destroy everything that cross their path. It is also believed that they were not beings originally from the New World, much like their predecessors, the Six Great Gods and the Eight Greed Kings who came here before them.

According to the dwarves' history of the Dwarf Kingdom, they laid waste to its country's capital Feo Berkana and killing most members of the royal family. In addition to that, many countries had been destroyed by the demon gods two hundred years ago, which was why there were very few countries with no more than two hundred years of history.

It wasn't just human kingdoms that were destroyed, countries composed of demi-humans and other heteromorphic species perished as well. Within their ranks would be the Demon God of Insects, which the Platinum Dragon Lord and Evileye has spoken of, when battling it alongside the Thirteen Heroes. Although its unknown if this being was one and the same kind they were fighting together.

Moreover, a being known as the king of the demons, the Demon God had led demons under his banner while having almost exterminated the entire world. The Demon God had met its end at the hands of the Thirteen Heroes, which vanquished it, and in a certain place it was still possible to see traces of that battle.

In addition to that, there was also a being known as the 'Dragon God' who became the last and final opponent for the Thirteen Heroes to have fought against during their adventures together. In the Web Novel, their battle marked the end of the Thirteen Heroes as they were said to be defeated by it. However, after returning from the battle, the Thirteen Heroes kept silent concerning the "Dragon God," and the truth remains in darkness.

The Undead King Arc
Nigun Grid Luin, upon witnessing the unbelievable powers of Ainz Ooal Gown and Albedo accused the two of being Evil Deities.

The Sealed Evil Tree Arc
Pinison Pol Perlia vaguely mentioned a group of powerful monsters that nearly destroyed the world. According to her one of these monsters hid in the Great Forest of Tob.

The Invaders of the Large Tomb Arc
When the workers from the Baharuth Empire began to explore the surface of the Great Tomb of Nazarick, they theorized it to be a ruin from a time before the rampage of the Evil Deities.

The Craftsman of Dwarf Arc
Gondo Firebeard mentioned the the Evil Deities in his explanation of the decline of Runecraft to Ainz Ooal Gown.

The Paladin of the Holy Kingdom Arc
When Jaldabaoth attacked the Holy Kingdom, Kelart Custodio estimated his power to be greater than that of the Evil Deities.

Strength
Evil Deities were extremely powerful according to the New World's standards, requiring the Thirteen Heroes to face and destroy each of them one by one. While at the same time, it seems apparent that the Evil Deities were not all equally powerful as they've been defeated in different ways.

However, most of them, if not all, did not exceed level 60. Some may have been weaker, as stated by the Nigun Grid Luin of the Sunlight Scripture that one such Evil Deity was actually slain by the Dominion Authority and its 7th tier attack spell "Holy Smite", which according to Ainz, is weak.

Based on the Web Novel, it seems the Evil Deities are capable of using 7th tier spells.

Trivia

 * In the Web Novel, it is hinted that the Evil Deities were beings that once served under the Six Great Gods.
 * The battle against the Demon God was one that transcended the racial barrier among the Thirteen Heroes.
 * According to Nigun of the Sunlight Scripture, he has heard that the Thirteen Heroes had defeated and sealed away the Evil Deities, implying that not all of them are completely wipe out for good.
 * It is speculated that Zy'tl Q'ae might also have been one of these Evil Deites.