Darth Ishtar is a Knight of Chaos for the Covenant Empire. He is a masked entity and all that is known about him is his strange connection to Cosmic Knight; Destin Marek.
Darth Ishtar revealed his existance by burning down a village on Kashyyyk, the home village of Destin Marek. The two were instantly able to feel a connection, a strange unexplainable one that would send the two on an ever lasting collision course, both representing the everlasting clash of light and darkness. Ishtar was revealed to be a Knight of the Chaotic Order, and an acting general for the Covenant Empire.