Resupply
The Empire employed and retrofitted Delta-class DX-9 stormtrooper transport Resupply to reload starfighters should they run out of warheads in battle. Resupply was present during the Capture and Defense of ZA-13 where the plant was being returned to Imperial control against rogue Grand Admiral Zaarin's insurrection and when the factory was supposed to be receiving upgrades and was attacked by a Rebel strike force during the process. The transport would then show up again at the operation to capture RS-32 to secure Mag Pulse warheads.
Behind the scenes
Resupply appears in Star Wars: TIE Fighter at Battle 8 Combats 4, 5 and 6. When the player runs out of missiles, Resupply will appear to reload your craft. Interestingly enough, the transport can be destroyed in either Combats 4 and 5, but appears again in Combat 6. This article assumes that the transport survives all events.