Darth Cognus was a female Iktotchi Sith Lord who operated in the years following the end of the New Sith Wars. Before she could formally begin her training, however, Bane's current apprentice, Darth Zannah, arrived to do battle with him for rights to the rank of Sith Master. Realizing that the two were evenly matched, Cognus did not interlope but instead pledged to serve the winner of the duel. Zannah emerged victorious, and Darth Cognus' life was then consecrated to the Order of Sith Lords. Cognus ascended to Sith Mastery years later, taking the three-eyed Human mutant Darth Millennial as her apprentice. She was ultimately forced to disavow him for blasphemy against Darth Bane's Rule of Two.