Who is the astromech droid that accompanies Luke?

The story behind the answer

Luke’s astromech rides in his X-wing, delivers Leia’s plea for help on Tatooine, and even fixes damage during the Death Star trench run—classic astromech duties like navigation, hyperspace calculations, and in-flight repairs. By contrast, C-3PO is a gold protocol droid focused on etiquette and translation; BB-8 is the spherical companion of Poe and Rey in the sequel era; K-2SO is a reprogrammed Imperial security droid from Rogue One.

Astromech droids are starfighter pit-crew partners, able to plug into ships and manage systems a pilot can’t. This plucky blue-and-white unit’s beeps and whistles (voiced by sound designer Ben Burtt) and on-screen ingenuity made it a saga mainstay—serving Anakin in the Clone Wars before teaming up with his son, forming a throughline across generations of the Skywalker story.