Darth Gean, a Twi'lek female, served as the apprentice to the Dark Lord of the Sith known as Darth Gravid, within the structure of the Order of the Sith Lords. Circa 533 BBY, Gean uncovered Gravid's scheme to eradicate all Sith artifacts, texts, and holocrons containing Sith wisdom, driven by his attempts to integrate Jedi principles into his Sith doctrines. Gean managed to breach the Force shields erected by Gravid around their shared bastion on the planet of Jaguada, leading to her successful assassination of her Sith Master. The battle, however, left Gean severely wounded, necessitating the use of prosthetic limbs. Eventually, she acquired her own apprentice, thereby perpetuating the lineage established by Darth Bane.
A Twi'lek female possessing Force sensitivity ultimately became the Sith apprentice to the Dark Lord of the Sith Darth Gravid and adopted the title of Darth Gean. During her time as Gravid's student, Gean aided her Sith Master in the construction of a bastion located on the planet called Jaguada. However, Gean's Master began to experience a decline in his mental state, stemming from his efforts to incorporate Jedi ideals, such as compassion and empathy, into his Sith teachings.
Around the year 533 BBY, Gravid—having decided that his collection of Sith holocrons and texts needed to be destroyed to facilitate the reconstruction of the Sith organization—utilized the Force to erect barriers surrounding his bastion and commenced the destruction of the Sith knowledge in his possession. Gean successfully breached the shields protecting their stronghold and engaged her Master in a duel. During the conflict, Gean sustained significant injuries when Gravid severed one of her arms and shoulders, along with the left portion of the Twi'lek's face and chest. Nonetheless, Gean gained the advantage, killing Gravid despite being unarmed.
Following the confrontation, Gean obtained prosthetic replacements for the limbs she had lost. She then took on an apprentice of her own and continued the pursuit of the Grand Plan—an initiative established by Darth Bane, the founder of the Order of the Sith Lords—aimed at overthrowing the Jedi Order and the Galactic Republic. By selecting her own apprentice, Gean upheld the Rule of Two, a principle also instituted by Bane that limited the Sith to a single Master and a single apprentice. Darth Plagueis shared the account of her actions with his apprentice, Darth Sidious, viewing her as courageous.
Upon discovering Darth Gravid's intention to eliminate the Sith teachings, Darth Gean demonstrated unwavering devotion to the dark side of the Force and the Sith Order by confronting and assassinating her Master, despite suffering severe injuries during their duel.
Darth Gean possessed Force sensitivity and demonstrated sufficient power to penetrate her Master's Force barriers surrounding his fortress. She also managed to survive the encounter with Gravid, despite sustaining grievous injuries and subsequently requiring prosthetic replacements. According to Darth Plagueis, the Twi'lek's Force abilities were not hindered by her cybernetic enhancements.
Darth Gean made her debut in the 2012 novel titled Darth Plagueis, authored by James Luceno. Her character was conceived to provide context for the history of the Order of the Sith Lords.