The Lost Jedi were Jedi who lived in the aftermath of the Jedi Civil War. The term commonly referred to members of the Jedi Order who survived under the First Jedi Purge that was waged by Darth Sion and Darth Nihilus' Dark Jedi faction, although the exiled Jedi and former leader of Darths Sion and Nihilus' Dark Jedi remnant, Kreia, referred to the followers of her student and fellow exiled Jedi, Meetra Surik, as the Lost Jedi; the true Jedi who would form the basis of a new Jedi Order.
Republic Intelligence reports indicated evidence that the Jedi Order had suffered even greater casualties after the war, when the First Jedi Purge was being perpetrated, but the information remained classified until some time after the devastation of Katarr, so the dissolution of the Order became one of the greatest mysteries of that time. The surviving Jedi had actually gone into self-imposed exile, hiding their presence until the Sith threat that was stalking them could be found.
Surviving members of the Jedi Council were known as Lost Jedi.
Jedi Masters and Councilors Zez-Kai Ell, Kavar, Vrook Lamar, Lonna Vash, and Atris, were Lost Jedi, as was Deesra Luur Jada. Master Vash travelled to Korriban, although she was murdered by Darth Sion. Atris resided in her secret Jedi Academy on Telos IV, unknown to the Sith and Jedi alike, as she was to attend the conclave on Katarr and was assumed to have died there. Just prior to the Battle of Telos IV, as agreed with her, Meetra Surik had what remained of the Jedi High Council assembled on Dantooine, but again Atris would not expose herself.
Vrook, Kavar, and Zez-Kai Ell all fell to the coming of Kreia, who murdered them in the ruins of the Jedi Enclave. After being defeated by Surik, Kreia referred to her student's disciples as the "true Jedi" upon which the future of the Order would be built. Having pledged themselves to Meetra Surik, the true Jedi became the foundation of a new Jedi Order.
Atton Rand, referred to as "the fool" by Kreia, desired no more than for external forces of the galaxy's conflict of light and dark to leave him be. However, having become acquainted with the Jedi Exile after meeting her at the Peragus Mining Facility, Rand confronted his past and pledged himself to the exile, deciding to be trained by the former Jedi, the last Jedi, the true Jedi, in order to help her.
The Echani hybrid Brianna (initially addressed to as "Handmaiden", and referred to as "the servant of Atris" by Kreia), who was once one of Atris' Handmaiden Sisters, was one of the Lost Jedi. According to Kreia's predictions, the Echani would succeed Atris as the Order's leading Jedi historian.
Mical was both a Jedi survivor and a follower of Meetra Surik.
Following Surik's departure for the Unknown Regions, Mical, referred to by Kreia as "the disciple," sat on the new Jedi High Council as a Jedi Master, and sentenced Atris—who had by then chosen to let go of her obsession with the Jedi and the dark side of the Force—for her crimes.
Mira, referred to as "the huntress" by Kreia, was once a restless bounty hunter who sought to be in a living environment—on Nar Shaddaa, where despite the misery of the place, the people there were active, their movements constant. When Mira awakened from her ignorance of the Force that connected all things, she became overwhelmed by the echoes of the Force that emanated from Nar Shaddaa's denizens. However, the Jedi Exile taught her to calm her mind in the Force, allowing Mira to sense the ebb and flow of life without succumbing to its frenzy.
Bao-Dur, referred to as "the alien" by Kreia, is an Iridonian Zabrak who was originally an engineer that served under Meetra Surik during the Mandalorian Wars. His creation and activation of the Mass Shadow Generator on Malachor V resulted in mass casualties from both the Republic and the Mandalorian fleet - as well as the utter devastation of the planet's surface; he also lost his right arm and replaced it with a mechanical one. Bao-Dur, a decade later, would reunite with his former general during their mission to find the lost members of the Jedi Council. With the Exile's help, Bao-Dur conquered his anger, and would follow his general in her footsteps - the footsteps of a Jedi.
The Miraluka Visas Marr, referred to as "the Blinded One" by Kreia, would return to her homeworld of Katarr and finally see the destruction that Darth Nihilus had caused to her now-barren world; she would ask the Exile to teach her to use the Force to save the galaxy from harm.