Nokris, Herald of Xol
Nokris, Herald of Xol is a Hive God, and the estranged son of Oryx, the Taken King and the herald of the Worm God, Xol, Will of the Thousands. Exiled by Oryx for his heresies, Nokris later traveled to Mars and was imprisoned in the polar ice by the Warmind Rasputin. 
Nokris was believed to be the older brother of Crota, but was disfavored by his father for his physical weakness. To make up for that weakness, Nokris instead honed his mind, learning magic and hoarding knowledge. He devised a plan to prove himself to Oryx by communing with the Worm Gods as he once did; however, while he succeeded, most of the worms rejected the disfavored son. Only Xol, Will of the Thousands remained to grant him an audience. Fearing an attack from Yul, the Honest Worm, Xol made a pact with the forgotten child. Nokris traded his heart for some of Xol's power and the secret of necromancy. 
Oryx soon learned about his son's activities and was furious. Nokris's actions were sacrilege, and necromancy was considered a heretical violation of the Sword Logic, for it disrupts the means of survival of the fittest. For his crimes, the King of the Hive exiled him and removed all references of his disowned son from the World's Grave and the Books of Sorrow. Only a statue remained.
Nokris was unperturbed. In exile he saw freedom and opportunity. He informed Xol that he would conquer the planet Mars in his name. After arriving, the two were met with resistance from the Warmind Rasputin, trapping them within the ice of Hellas Basin.
The Taken and Red Wars
The only reference to Nokris known to the Guardians prior to his awakening on Mars was a statue found in the Dreadnaught near the Altar of Oryx, beside similar statues of Crota and Oryx. The Guardian's Ghost infers it is a Hive god from the accompanying Hive glyphs but couldn't recognize the symbol. At Eris Morn's request, Asher Mir scoured his library for references to Nokris but found none..
War with The Warmind
After the deaths of Oryx and Crota, and the end of the Red War, Nokris and his master were awakened when their entrapping ice began to melt; an effect of the Traveler's waking. Together, they sought the destruction of the Warmind Rasputin for their imprisonment and engaged once more with the Warmind. However, interference came in the form of the Guardian working with Ana Bray. Nokris encountered the Guardian during their mission of using a small shard of the Traveler as bait to lure Xol out and destroy him. However, Nokris faced them instead and fought the Guardian in a fierce battle. Despite his power, Nokris was incinerated by the Guardian, having failed to protect Xol from its destruction.
Nokris is the boss of the Strange Terrain mission and is encountered at Xol's feeding grounds. He fights primarily by firing Solar blasts at the player and occasionally summoning Hive to assist him. Every third part of his health, Nokris will break two of the pillars in the arena and retreat to the gate at the front of the battlefield. Nokris will proceed to shield himself in an immune shield. To break the shield, the player must find the large green rock that came out of one of the two pillars Nokris broke, find the recently resurrected Ugul Gar Knights, kill them, and throw the dropped relic at one of the pillars and then the next to stun Nokris and take down his shield. During the first immunity phase, he will stand still while summoning Hive, during his second phase, he will begin firing darkness blasts at rapid succession, and at his last phase, he will begin moving around the arena, using his Dying Star ability.
List of appearances