Carth Onasi is the firt party member the player meets when playing Knights of the Old Republic. Carth is an officer of the Republic Fleet and a veteran of both the Mandalorian and Sith Wars. Carth believes his family was killed during an attack on his home world Telos. The officer in charge of the Sith fleet that destoryed Telos was Admiral Saul Karath. Admiral Karath was a mentor and friend to Carth during the Mandalorian War and Karath's decision to fight for the Sith left Carth deeply wounded. His leadership in the attack on his home world only made Carth more determined to exact his revenge with Karath's death.
Carth is an expert pilot and flies the ship used in the game, the Ebon Hawk. He has a significant sub plot arise for his character in the Sith Acadamy on Korriban.
Personally, Carth is deeply distrustful of the Jedi. This stems in part from knowing how the leaders of the Republic war effort against the Mandalorians, Revan and Malak, fell to the Dark Side, starting the Sith conquest of Republic space, and the seemingly mysterious and obtuse way the Jedi Counsel makes major decisions. He views them as unnecessarily secretive and not completely aligned with the needs of the citizens of the republic. His antipathy is only strengthened by the behavior of Bastila Shan. However, this distrust never sways him from his total commitment to the Republic war effort against the Sith and is probably the most morally committed character of the game.