Born Dessel in 1026 B.B.Y, the man later know as Darth Bane was raised as a poor minor on the outer rim planet Apatros. After killing a Republic soldier, he was endangered of being arrested by the Galactic Republic. Aided by his friend, Groshik, he escaped off world to serve the Sith Brotherhood of Darkness.
Des began his career as a foot soldier in the Gloom Walkers unit, he was discovered as being Force sensitive and was taken to the Sith Academy on Korriban. It was here that he was dubbed Bane. Utilizing the name is abusive drunken father would call him as a derogatory term.
While at the academy, though one of the most promising students, he briefly lost his faith in the dark side of the Force. He regained it; however, he lost his confidence in the Brotherhood of Darkness. Bane grew to detest the Leader of the Brotherhood, Lord Kaan. He believed him to be foolish and a coward. Bane believed that the Sith could not truly come to full power if they were too busy fighting themselves.
Deserting the Sith Brotherhood, he went to the planet Lehon and studied the holocron of Darth Revan, and, armed with new knowledge. From the holocron, Bane learned a tremendous deal about the dark side and Sith, more than he had learned in his entire time at the academy. The knowledge he gained from this holocron validated his view that the Brotherhood needed to be destroyed for the Sith to conquer the Jedi. Bane, through manipulation, had Kaan detonate a thought bomb on the planet Ruusan. This killed all Force-senstives in the vicinity. Unaware of Bane’s existence, the Jedi Order believed the Sith to now be extinct.
Bane then instituted a Rule of Two, which stated that there could be only two Sith to avoid the infighting that had plagued the Sith for millennia. He also took both the title of Darth and an apprentice named Darth Zannah.
Before departing Ruusan, the Dark Lord took his apprentice to the Sith camp, where a group of mercenaries were looting the site. The mercenaries had fought for the Sith, only to abandon the cause after Kaan led his troops into the cave. Disgusted with those who were loyal only to money, Bane attacked the mercenaries, quickly killing four of them. Though the other two fled, Bane dismissed chasing them down because he saw no need in it; the two were soldiers for hire and thus would be believed by no one. Bane also believed that the use of rumors of the Sith's continued existence could prove useful by confusing the Jedi Order and spreading fear and chaos.
After leaving Ruusan, Bane headed for Dxun in the Valcyn. However, while in transit, the ghostly spirit of Qordis appeared and chided him for abandoning the Brotherhood. Bane insisted that he was only furthering the Sith cause, but he was enraged by Qordis's claims and began to doubt his sanity. After spending several days stuck in the starfighter's cockpit listening to Qordis curse him, Bane finally released his anger when the Valcyn entered Dxun's atmosphere. Unleashing a blast of dark side energy, he caused Qordis's spirit to vanish, but also damaged the ship, forcing him to make a crash-landing.
Bane, however, managed to survive the crash even though his ship was destroyed upon impacting the moon. Though Qordis continued to mock him, insisting that he would die on Dxun, Bane ignored his pleas, and marched onwards to where he sensed Freedon Nadd's tomb to be. Bane was guided by the spirit of Kaan, who, unlike Qordis, did not make any attempts to attack him. He was able to make it to the tomb and immediately began searching it. There, Bane located Nadd's holocron. However, as Bane moved to claim it, he was attacked by several beetle-like creatures in the chamber where the holocron was. Bane was unable to keep them away, and two of them attached to his skin. As they could not be removed, this caused the Sith Lord to be in a perpetual state of pain from the creatures gnawing on his skin, only enhanced as they began to slowly multiply and spread across his body.
As he began to study Nadd's holocron, Bane discovered that the creatures were parasites called orbalisks that could not be removed. Though they caused the Dark Lord to be in constant pain, their shells were impenetrable; even lightsabers could not crack them. The orbalisks covering nearly all of Bane's body formed an impervious suit of armor. Furthermore, they gave Bane tremendous healing abilities, and pumped chemicals into his bloodstream, enhancing his connection to the Force while increasing his rage, thus boosting his power in battle. Because they increased his capabilities while causing him to suffer unending pain, Bane viewed the creatures as both a gift and a curse. After spending days studying from the holocron, Bane exited the tomb and headed to Onderon. Taming a flying drexl using the powers of the dark side, he mounted it and rode towards the edge of the atmosphere where Dxun came close to Onderon's atmosphere. Once on Onderon he found Zannah being threatened by a group of Beast Riders. Onboard the drexl, Bane attacked the Riders, slaughtering them and their mounts. Now that his apprentice had proven herself, Bane planned to begin training Zannah.
In 990 BBY, ten years after the destruction of the Brotherhood, Bane sought to learn how to create a holocron, through which he would pass down his knowledge to future Sith Lords. The Sith journeyed to the Deep Core world of Tython to locate the Sith holocron of the ancient Dark Lord Belia Darzu. However, while Bane was on Tython, the Jedi Order learned of his existence, and sent a group of Jedi to kill him and his apprentice. Once the Jedi arrived, they confronted the two Sith in Darzu's fortress. Though outnumbered, the Sith were able to defeat the Jedi; however, Bane was grievously injured by his own Force lightning. This killed the orbalisks who in response, released a deadly poison to kill Bane.
Zannah took him to Ambria, where she convinced the healer Caleb to help them. Caleb, who had previously healed Bane years earlier, notified the Jedi Council. When Bane awoke days later, he was free of the orbalisks and cured of their poison. Zannah told him what she had done, and he expressed his disappointment before asking her to kill him, sparing him the life of a prisoner of the Jedi. However, Zannah had had another plan in mind all along. She used her powers to drive her cousin Darovit insane. Zannah killed Caleb, then hid herself and Bane. When the Jedi arrived, they killed Darovit, believing him to be the Sith Lord. Thus, the Sith were believed destroyed.
A decade later, Bane and Zannah had relocated to Ciutric IV, where they owned a large mansion. The two possessed immense wealth, which they used to continue to build up their network of spies and plan for the time when the Sith could destroy the Jedi. Bane had also created a holocron which held all his knowledge, and, posing as a simple collector, the Dark Lord had acquired a great number of Sith artifacts.
However, Bane began to worry that his apprentice was too weak to overthrow him and assume the mantle of Dark Lord of the Sith, as was necessary under the Rule of Two. He began to research the secrets to prolonging his life by transferring his essence to another body, and traveled to Prakith, where he claimed the holocron of the ancient Darth Andeddu. After returning from Prakith, Bane was ambushed by a team of assassins hired by Caleb's daughter, Serra, and was captured. Taken to Doan, Bane was imprisoned and tortured, only to covertly gain his freedom soon afterward.
Encountering Zannah on Doan, Bane dueled his apprentice, who sought to become the new Dark Lord of the Sith. The fight ended in a draw, with Bane escaping and heading to Ambria with Darth Cognus, an Iktotchi assassin skilled in use of the dark side whom Bane planned to take as his apprentice if Zannah proved herself weak and unworthy.
There, Bane and Zannah engaged in a fateful duel that resulted in the death of Darth Bane after a climatic mental battle with his body being destroyed. Zannah claiming the title of Dark Lord of the Sith. Bane tried to initiate the ritual of essence transfer but failed to control his apprentice's body. Part of Darth Bane's soul seemed to live in Zannah's body after the failed ritual. But most of his spirit was thrown into the void, causing him an eternity of suffering. Nearly a millennium later, Bane's Sith Order defeated the Jedi Order and overthrew the Republic by Darth Sidious and Darth Vader.
However, the dark lords would fall and the Rule of Two would be finished when Anakin Skywalker killed Sidious during the Battle of Endor brining Darth Bane’s Sith line to a close.