Y 4 was the designation given to a two-person BTL-S3 Y-wing Starfighter utilized by the Alliance to Restore the Republic.
Following the Battle of Yavin by a few months, it was moved to Docking Bay 12 of a refueling station orbiting Devaron. The purpose of this was so that Rebel pilot Luke Skywalker could utilize it for a mission aimed at recovering Imperial communication logs. These logs had been intercepted by various rebel cells along the Shipwrights' Trace. Accompanied by C-3PO and R2-D2, Skywalker journeyed to the Tertiary Usaita system, where the starfighter came under attack from three TIE fighters as well as the Razor-class frigate named Kreuge's Revenge. The Y 4 sustained damage which forced Skywalker to retreat from the conflict and return to Devaron. Upon landing in Tikaroo, he entrusted the vessel to Kivas for repairs. After an extended period at the Temple of Eedit, Skywalker retrieved the repaired ship and departed from the planet.