Ralesk was a Sith male Human. He was a leading assassin in Lord Grathan's service throughout the Cold War.
Lord Grathan dispatched him in 3643 BBY with the task of assassinating Darth Baras' apprentice as punishment for the murders of Beelzlit and Cellvanta Grathan. Ralesk's presence was noted in the hangar when the apprentice received orders to locate Nomen Karr and Jaesa Willsaam. Seeking to gain favor with his master, Ralesk confronted the Sith Warrior, but the apprentice defeated and killed him.