In the Star Wars movies
Original trilogy
In the original Star Wars trilogy, Darth Vader is the primary antagonist: a dark, ruthless figure, out to capture, torture, or kill the protagonists to prevent them from thwarting the Empire.
A New Hope
In A New Hope, Vader leads a unit of Stormtroopers in a boarding action on the Tantive IV
Darth Vader is introduced in Star Wars Episode IV: A New Hope as a dark, menacing figure whose assault team has just taken control of the Tantive IV (a consular ship in orbit above the planet Tatooine), in an attempt to retrieve plans for the Empire’s new weapon, the Death Star, which have been stolen by the Rebel Alliance. Vader makes his first appearance boarding the ship in order to directly assess the situation.
Imperial stormtroopers under his command capture Princess Leia Organa (Carrie Fisher) of Alderaan (who is secretly a leader of the Rebel Alliance), but not before her droids R2-D2 (Kenny Baker) and C-3PO (Anthony Daniels) escape with the plans to the planet below. Vader and his forces, with their prisoner, return to their transport, an Imperial Star Destroyer, which subsequently destroys the consular ship.
Below on Tatooine, Luke Skywalker (Mark Hamill) witnesses the destruction of the ship through macro-binoculars. Later, Luke’s Uncle Owen (Phil Brown) and Aunt Beru (Shelagh Fraser)
are killed by stormtroopers who were attempting to track down the missing droids, which the family had purchased as farm help. Meanwhile, Luke (who has the missing droids) learns from "Old Ben" Kenobi (Alec Guinness)- a local hermit who once went by the name Obi-Wan- of Vader’s apparent role in the death of Luke’s father. Luke and thedroids, with Kenobi’s help, avoid the stormtroopers, and eventually
secure passage on board a smuggling ship known as the Millennium Falcon, intending on deliveringthe droids (and thus the plans) to the Rebel Alliance.
Upon arriving at the Death Star, at a meeting, Admiral Motti (Richard LeParmentier)ridicules Vader’s "sad devotion" to the Force, saying that it has nothelped in finding the plans, or the rebel base. Vader responds by using the dark side of the Force to choke the officer, stopping only when Imperial leader Grand Moff Tarkin (Peter Cushing) intervenes.
Following the meeting, Vader tortures Princess Leia in an attempt to locate the hidden rebel base.
Eventually the Millennium Falcon is captured by the Death Star’s tractor beam. After attempting to disable the tractor beam machinery, Kenobi, who Luke has discovered is a Jedi master, is forced to face Vader in a lightsaber duel.
While Vader fights Kenobi, eventually striking him down, the other
characters use the opportunity to escape with the recently rescued
Princess Leia. However Vader had anticipated this eventuality, and had
a homing beacon hidden aboard the Millennium Falcon in order to trace them to the rebel base.
Using the plans, the Rebel Alliance makes a desperate attempt to
destroy the Death Star through a weakness in its design. Vader and his
flight team join the defense of the station, intercepting any rebel
fighters attempting to exploit the weakness. At the climax of the film,
Vader, in his TIE fighter, is about to destroy Luke’s X-wing fighter en route to destroy the Death Star, when the Millennium Falcon intervenes sending Vader’s fights had showed the fact
that Vader was intended to be a tragic character.
The name Darth Vader as a cultural metaphor
Vader’s name has become a synonym
for evil. Lucas has pointed to Vader’s iconic status as a reason he
made the prequel movies, since he felt the icon oved say, well, he’s the Darth Vader of the
administration.