Depa Billaba was a Chalatan Jedi Master that served on the Jedi Council during the waning days of the Old Republic. The Master Billaba entered the Jedi Order at six months old when she was rescued from space pirates by Jedi Master Mace Windu after the pirates left her an orphan by killing her parents. In honor of her parents, Depa Billaba incorporated the teachings of the Chalactan Adepts into her Jedi training. The Chalactan Adepts were a group of mystic philosophers seeking enlightenment. Those that obtained Chalactan Enlightenment were wore the Greater Mark of Illumination that symbolized the universe and Uncloseable Eye that saw it. Depa Billaba wore both the Greater and Lesser Mark of Illumination when her training under the Chalactan Adepts was complete.

As a Jedi, Depa Billaba was apprenticed to the same Jedi who had saved her as an infant, Mace Windu. Under his tutelage, Depa Billaba grew into equal parts philosopher Jedi and warrior Jedi. Her training as a Chalactan adept allowed her to be attuned to the minds of her peers. Also, as Mace Windu was one of the founders of the seventh form of lightsaber combat, Vaapad, which he taught to Depa Billaba. She was one of the few Jedi of the Order to master the form. Depa Billaba eventually attained the rank of Jedi Knight, then Master, and Mace Windu was honored when his former student was chosen to join him on the Jedi Council.

While a member of the Jedi Council, Depa Billaba was involved in many of the crises that the Jedi Order was forced to deal with. Shortly before the Battle of Naboo, Depa Billaba joined the Jedi in weathering the crisis resulting from actions by a militant wing of the Nebula Front. The organization opposed government controls on free trade and privileges for large corporations. The group began attacking Trade Federation interests, and the Jedi learned of the group's plans to assassinate Chancellor Valorum. Depa Billiaba joined a team of Jedi sent to Asmeru in an attempt to negotiate with the group. However, the negotiations were simply set up as a way to ambush and distract the Jedi as the assassination plans were put into place. Luckily the Jedi were able to stop the assassination attempt and save Chancellor Valorum's life.