"My enemies...I am Exar Kun."
-Exar Kun

Exar Kun was a highly talented Jedi apprentice under the tutelage of Master Vodo-Siosk Baas. After being forced to fall to the dark side of the Force by ancient Sith spirits, he became one of the galaxy's most powerful and dangerous Sith Lords, taking Ulic Qel-Droma as his apprentice. He then initiated the Great Sith War, tearing the Galactic Republic apart through several battles, until he sealed his own spirit away in a Massassi Temple on Yavin 4.

Thousands of years later Kun's spirit would return to wreak havoc on Luke Skywalker's Jedi Praxeum. He possessed two students, Gantoris and Kyp Durron, turning them to the dark side and eventually killing Gantoris. He also succeeded in taking Luke's soul from his body, but was eventually defeated by the combined power of Luke's students.