Fire Across the Galaxy
JJR-579 was patrolling hangar bay 5 aboard the Sovereign, with JTN-303, while it was in orbit over Mustafar. As he oversaw a group of TIE Fighters landing in the hangar, he and his comrade noticed an oddly-colored fighter. When the Stormtroopers went to investigate it, the rigged fighter set off an electromagnetic pulse that partially disabled the ship and knocked 579 and JTN-303 unconscious. The fighter was sent by a group of rebels in a mission to save Kanan Jarrus, who was being held captive on board the Sovereign. His fate is unknown. He is presumed killed in the explosion of the Sovereign or escaped in time.
- "Fire Across the Galaxy" (First appearance)