Mangroth

Mangroth was a humanoid creature who was born in the Underworld eventually Mangroth left the Underworld and travelled to Eastward where the goblins swore allegiance to him, After this Mangroth and his army travelled to Westward where they settled in the Northern Mountains and built the forts of Angorium and Lamacher while in Angorium Mangroth formed the Kingdom of Elmros and declared himself as the first King of Darkness eventually Mangroth found the devils other half and the God of the demons resurrected Self,Sanra, at this point Sanra had no idea who he was and where he came from however Mangroth taught him everything eventually Sanra became Mangroth's friend with Mangroth seeing him as a son eventually Mangroth was killed and so Sanra succeeded him as King of Darkness.

Later on Mangroth returns to life in To Darkness we Descend. Although he lives very shortly, and becomes more powerful then he ever was.