The Y-wing, built by Koensayr, is the slowest, most ungainly Rebel starfighter in the fictional Star Wars universe. In the movies, it is seen in both A New Hope and Return of the Jedi. The craft carries two laser cannons, two ion cannons, and two proton torpedo launchers. An astromech droid, such as an R2 unit, plugs into a socket in the craft, to act as a copilot.

The Y-Wing was already obsolete by the time of the Galactic Civil War, but it is still fielded by many planetary defense forces, mercenaries and pirates. It is a rugged design, but it has some design flaws requiring constant maintenance. This lead many crews to remove the superficial hull plating.

There were two common designs during the time of the movies. The first, the BTL-S3, was a two-man strike starfighter. The weapons systems officer typically operated the ion cannon turret when needed. This design was supplanted in most services by the BTL-A4, which was a one-man starfighter. The ion cannon turret was typically locked forwards in this design, although some pilots chose to lock it facing aft for extra cover. In addition, this variant boasted much greater endurance (as much as three times longer) over its earlier predecessor. The Rebel Alliance apparently did not consider the deletion of the weapons systems officer to be a disadvantage, nor the "loss" of a trainable ion cannon. An additional, though less common, variant was equipped with advanced scanners and extended fuel supplies in place of the weapons; the Y-Wing "LongProbe" is used primarily for long range scouting missions.

Despite its shortcomings in speed and maneuverability, the Y-Wing is an extremely tough craft, with heavier shielding than the X-Wing. It can withstand many blasts from a laser cannon, and it is quite difficult to destroy. The Y-Wing was often used as an assault craft, to attack enemy capital ships directly in conjunction with B-Wings. X-Wings and A-Wings were used to distract the enemy fighters and the ship's gunners, to allow the Y-Wings and B-Wings to focus their fire on the capital ship. This tactic is similar to the "A-Wing Slash", which involves solely X-Wings and A-Wings.

In the X-wing computer game series it is further explained that the Y-Wing was a relatively early design, explaining its slow speed and relatively poor maneuverability. However, in the games its deficiencies are partly compensated for by the heavy missile load it can carry, and its unique (until the introduction of the B-wing in later games) ability to paralyze craft with ion cannon fire without destroying them.

The most famous Y-Wing pilot is Horton Salm, who flew in the battle of Endor.