Unidentified rogue Jedi

During the Old Republic-era, a Force-sensitive individual was a member of the Jedi Order. At some point, he began studying the forbidden teachings of the dark side of the Force and believed that the true potential of a Jedi involved tapping into the dark side, as opposed to embracing the contemplation and passivity of the light side. The Jedi High Council, upset by the beliefs of this Jedi, exiled him from the Jedi Order. The fallen Jedi gained a number of followers, and their actions led to formation of the Sith, an order born during the Hundred-Year Darkness. The Sith became the ancient and mortal enemies of the Jedi Order. In time, the name of the Sith Order's founder was lost to history.

The rogue Jedi was first mentioned within canon in the Encyclopedia entry for the Sith on StarWars.com. According to the 2021 book The Odyssey of Star Wars: An Epic Poem written by Jack Mitchell, the Sith Lord Darth Sidious honored the founder with a statue made out of the hardest crystal he could find, which he displayed alongside a statue of the Sith Lord Darth Bane, who had reformed the Sith under the Rule of Two, on the DS-2 Death Star II Mobile Battle Station. According to Mitchell, these statues should not be taken as "canonical" nor "anti–canonical," given that no such statues appear within Star Wars: Episode VI Return of the Jedi, and he has explained that he mentioned them to provide detail on the Sith as if it was an epic Greek poem.

In Star Wars Legends, the exiled Jedi who started the Sith was identified as Ajunta Pall.