Eremin Tarn was a person with Force-sensitive abilities who existed during the time that the Galactic Republic was in power, during its reign. When Tarn turned thirteen years old, Jedi Master Maks Leem chose him to be her Jedi Padawan, and he was trained in how to use the Force. He then served as a guardian of the Republic within the Jedi Order. Tarn was a stubborn but honorable student who often challenged the authority of others, even his own Master.
As the galactic Clone Wars started in 22 BBY, Tarn became one of the many Jedi who lost faith in the Jedi Order. He chose to leave the Order and became a disciple of Jedi Master Sian Jeisel, who held the belief that the Jedi should have opposed the seemingly corrupt Republic instead of protecting it from the Confederacy of Independent Systems. In 19 BBY, Leem spoke with Grand Master Yoda of the Jedi Order about her previous Padawans, and voiced her sorrow over Tarn's departure from the Order to follow Jeisel.
The character of Eremin Tarn was referenced in Yoda: Dark Rendezvous, a book by Sean Stewart that was released in 2004.