JTN-303 was a stormtrooper of the male persuasion, serving the Galactic Empire as part of the Imperial Army. Five years before the Battle of Yavin, he found himself posted on Lothal aboard Grand Moff Tarkin's Imperial Star Destroyer.
While aboard the Sovereign, Tarkin's vessel, JTN-303's assignment involved the transport of Jedi Knight Kanan Jarrus to Mustafar for what was to be his ultimate interrogation. JTN's post was at the TIE Fighter Depot. When a Rebel TIE fighter flew into the hangar, he initially admired its appearance, but it then unleashed a stun blast, incapacitating both JTN and his partner. This event was a component of a larger operation to rescue Jarrus. By the time Jarrus and his comrades made their way back to the hangar, JTN was no longer present at the location where he had been stunned.