Evil Deities

Evil Deities or Demon Gods were legendary figures in the New World, who appeared some time after the demise of the Eight Greed Kings. Evil Deities spread chaos and destruction throughout the land until they were eventually defeated one by one 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 in their path. It is also believed that they were not beings originally from the New World, much like the Six Great Gods and the Eight Greed Kings.

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.

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

Strength
They 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, the demon gods 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.

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 Demon Gods, 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 Demon Gods.