Wikipedia
Ishum
Ishum is a minor god in Akkadian mythology, the brother of Shamash and an attendant of Erra. He may have been a god of fire and, according to texts, led the gods in war as a herald but was nonetheless generally regarded as benevolent. Ishum is known particularly from the Babylonian legend of Erra and Ishum. He developed from the Sumerian figure of Endursaga.
In the Kate Daniels book series written by fantasy novelist Ilona Andrews, Ishum (known in modern times as Roland) is a powerful immortal and the main antagonist of the series.