Was it true Exar Kun this is copy and paste from wiki
Exar Kun was a rash and talented youth; qualities that resulted in considerable arrogance, a dangerous trait for a
Jedi. During his training, he frequently dueled with and defeated his fellow Padawans, Sylvar and Crado.
Crado was a Cathar male from the planet Cathar, and a Jedi apprentice of Master Vodo-Siosk Baas. He studied the Force, along with his fellow Cathar and life-mate, Sylvar, as well as the Human Exar Kun, on the world of Dantooine. After years of rivalry, Crado chose to follow his fellow student when Kun became Dark Lord of the Sith and promised to renew the Jedi Order by combining its teachings with his own Sith knowledge.