Tamith Kai was a female Human Nightsister. Originating from the Great Canyon Clan on the planet of Dathomir, she later served as an assistant instructor to Brakiss at the infamous Shadow Academy.
When the Great Canyon Clan of Dathomir forged an alliance with Brakiss's Shadow Academy, Tamith Kai volunteered to act as Brakiss's representative. She ultimately rose to the position of assistant instructor within the Shadow Academy, taking on responsibilities that included recruitment, combat instruction, and maintaining discipline.
Tamith Kai dedicated herself to training her students, patiently awaiting the order to escalate recruitment efforts through force, which came in 23 ABY. She spearheaded the assault on GemDiver Station, masterminding the abduction of Jedi trainees Jacen Solo, Jaina Solo, and Lowbacca. Subsequently, she and Brakiss divided the newly acquired recruits between themselves for further instruction.
Following Lowbacca and Jaina's disruption of one of Brakiss's lectures, Brakiss determined that the training of the new recruits should be shared between himself and Tamith Kai. She was assigned to train Lowbacca, who had displayed a propensity for anger when Brakiss punished Jaina for her insubordination. Tamith Kai intended to exploit the young Wookiee's volatile temper to draw him toward the dark side, even resorting to methods of torture. When Lowbacca succumbed to his rage, destroying a sonic generator beyond repair, Tamith Kai rewarded him by returning a reprogrammed Em Teedee to him. However, the little translator droid's heightened capacity for irritation and newfound allegiance to the Second Imperium produced an effect opposite to what was intended on Lowbacca.
The endeavors of Brakiss and Tamith Kai proved futile, as Luke Skywalker and Tenel Ka successfully thwarted their scheme. As the twins and Lowbacca made their escape, Tamith Kai confronted Tenel Ka, vowing to corrupt her to the dark side after eliminating the young warrior's companions. Tenel Ka retaliated by inflicting a wound on Tamith Kai's knee. This confrontation fueled a deep-seated animosity between the two Dathomiri.
In the aftermath of that failure, Brakiss concluded that capturing such prominent individuals would only attract unwelcome attention. The Shadow Academy would instead focus on recruiting disadvantaged youths from Coruscant and other planets to bolster the ranks of the Second Imperium. Those with Force-sensitive abilities would be trained as Dark Jedi, while those without could still serve as valuable stormtroopers or TIE pilots.
Alongside Garowyn, Tamith Kai accompanied her new apprentice, Vilas, to the undercity of Coruscant to carry out their mission. More often than not, they employed the Force to simply persuade their targets to accompany them, but some, such as Zekk, proved more resistant and required stunning before being transported to the Shadow Academy. However, once aboard the space station, he ceased to cause further trouble.
Tamith Kai developed a strong dislike for Zekk, primarily because he surpassed her own apprentice Vilas in his mastery of the dark side. After Zekk defeated Vilas in a contest to determine the Shadow Academy's Darkest Knight, Tamith Kai's animosity towards Zekk escalated into outright hostility. Later, when Brakiss paired them together for a raid on Kashyyyk, Tamith Kai voiced her distrust of the Darkest Knight, questioning his loyalty. Upon discovering that Jacen, Jaina, Tenel Ka, and Lowbacca were present on Kashyyyk, she attempted to force Zekk to prove his allegiance. She reasoned that a truly loyal Zekk would unhesitatingly kill his former friends. His failure to do so only deepened her suspicions.
Shortly thereafter, both Zekk and Tamith Kai were chosen to spearhead the assault on the Jedi Praxeum. While Zekk opted to lead the Dark Jedi forces on the ground, Tamith Kai chose to command from a floating platform. Following a duel with Tenel Ka, the warrior girl sabotaged the platform on which she stood. The platform subsequently crashed into a river, resulting in Tamith Kai's death.