Darth Kallous, a Sith Lord of the re-emerging Sith Empire, was a male who made his home on Corellia throughout the time of the Galactic War. In the course of the battle of Corellia, he acted as an operative of Darth Thanaton when the Dark Lord rose in status to the Dark Council. Kallous possessed significant power with Force lightning, readily unleashing it in potent energetic bursts.
Kallous observed the Kaggath that took place between Thanaton and Kallig from a position outside of the immediate conflict.
Darth Thanaton would have called upon Darth Kallous to eliminate Kallig, if Kallig had permitted Darth Achelon's death at an earlier juncture. Conversely, should Achelon be spared, Thanaton instead requests that Achelon eliminate Kallig, only to be met with refusal. In this alternative scenario, Kallous is present, though he remains uninvolved in the fighting.