A Sith hopeful, also known as a Prospective Sith was what many Sith on Korriban called an individual who aspired to enroll in the Sith Academy that had been established on that world during the Jedi Civil War. Many of these were normal individuals who sought a better lifestyle, or at least to get in on what they saw as the winning side, while others were former Jedi who had been seduced by the dark side.
During the Jedi Civil War, many hopefuls attempted to join the Sith Academy on the planet Korriban, hoping to wield the dark side of the Force. To be accepted into the Sith Academy, a prospect had to be impressive enough a to be given a Sith Medallion. The final decision rested with the Twi'lek Sith Yuthura Ban, apprenticed to the Academy's Master, Uthar Wynn, who would then bring the prospective Sith in to be trained. However, because Sith were intolerable of failure, many initiates ended up getting killed.
Shaardan harasses a group of Sith hopefuls.
On one occasion, the student Shaardan grew tired with three hopefuls who kept giving incorrect answers regarding moral questions about the Sith. He was so exhausted from this that he couldn't make up his mind about what to do with them, but his most preferable choice was to kill them with Force lightning. When he asked an amnesiac Revan what should be done with them, Revan convinced him to let them go.
Other prospective Sith were tricked into doing foolish tasks for the amusement of other Sith. Mekel, in particular convinced a few to stand in one place promising to admit whichever person was able to take the longest without food, water, or sleep. However, he never intended to admit any into the academy and Revan objected to this, to which Mekel only left with a huff and a half-hearted threat. After Mekel left, Revan convinced the hopefuls to abandon their quest to join the Sith, convincing some of the truth, while lying to others and telling them they didn't make the cut.
When Revan managed to acquire a Sith Medallion, he was approached by a couple of hopefuls who also desired such devices. He eventually convinced them to abandon their quest to get one. Still others meandered around Dreshdae settlement and its cantina, The Drunk Side, or the Czerka Corporation sector offices.
Sith hopefuls appear in the game Star Wars: Knights of the Old Republic and interact with the player as part of the gameplay on Korriban. While the term "Sith Hopeful" is used in player dialogue with the NPCs there, the game's "targeting indicator" labels them as "Prospective Sith."