User blog comment:B214/Volume 23 discussion blog/@comment-201.19.107.104-20170508231409/@comment-29963364-20170509201815

An "Evil God" is a God who seeks to conquer or bring chaos and/or destruction to the world.

 Loki 


 * Betrays the Norse Gods and uses his children/creations, Midgardsormr & Fenrir, to kill various Gods and destroy the world (although it does get "reborn" afterwards).

 Balor 


 * The direct enemy of Lugh, the God of the Sun, Light (duh), and all things good. Balor was a God who braught carnage to mankind and the world.

There are other examples, but these two are the biggest examples I could think of. And they are characters in the DxD series (a piece of Balor's conciousness is inside Gasper Sacred Gear).