A Lambda-class T-4a shuttle known as ST 321 functioned as the dedicated transport for Darth Vader, the Dark Lord of the Sith, during the concluding phases of the Galactic Civil War. In the year 4 ABY, this shuttle, ST 321, conveyed the Sith Lord to the DS-2 Death Star II Mobile Battle Station, which was in its final construction stages while positioned above the moon of Endor. Remarkably, ST 321 survived the destruction of the battle station during the Battle of Endor, thanks to Luke Skywalker who piloted the shuttle out of the second Death Star just before its catastrophic explosion.
The Lambda-class T-4a shuttle ST 321 provided transportation for Darth Vader, the principal enforcer and secret Sith apprentice serving Emperor Palpatine, the absolute ruler of the Galactic Empire. In 4 ABY, Vader was transported by ST 321 to the second Death Star, an Imperial planet-destroying battle station that was being assembled in orbit around Endor, also known as the Sanctuary Moon.
Although a captain was assigned to ST 321, Vader would occasionally pilot the craft himself. A notable instance occurred shortly after the Emperor's arrival on the Death Star, when he flew the shuttle from the battle station down to the Imperial base that guarded its shield generator on the Sanctuary Moon. Soon after, while a large-scale battle raged in orbit between the Empire and the opposing Alliance to Restore the Republic, Vader engaged in a duel with his son, Luke Skywalker, a hero of the Alliance, aboard the Death Star. Ultimately, Vader chose to redeem himself by betraying the Emperor to save his son, but suffered a fatal wound in the process. With the Death Star on the verge of exploding, Skywalker used ST 321 to escape the doomed battle station, carrying his deceased father with him.
After escaping the rapidly disintegrating Death Star, Vader's shuttle was nearly intercepted by Shara Bey of the Alliance's Green Squadron. However, upon recognizing Luke Skywalker as a friendly pilot, she provided cover for the shuttle against approaching TIE/IN interceptors.
ST 321 made a subsequent appearance in the 1997 re-release of Star Wars: Episode V The Empire Strikes Back when Darth Vader returned to the Executor during the film's climax. This was largely due to the reuse of the scene depicting Darth Vader's arrival on the Death Star II from Star Wars: Episode VI Return of the Jedi.