He was once known as Anakin Skywalker, a slave child from Tatooine taken in and trained by the Jedi Order. He grew to become a powerful wielder of the Force and a hero of the Clone Wars, until the fateful day when he was seduced by the dark side of the Force. Desperate to save the life of his beloved wife, Skywalker was tempted to the dark side by Republic Chancellor Palpatine, secretly known as Darth Sidious, the Dark Lord of the Sith. Anakin Skywalker pledged himself to Palpatine's teachings and was dubbed Darth Vader.
After becoming Palpatine's new Sith apprentice, Darth Vader helped the Emperor hunt down and destroy the Jedi Knights scattered across the Galaxy and brought an end to the Clone Wars by personally slaughtering the leaders of the Confederacy of Independent Systems. His betrayal of the Jedi and the Republic brought him into direct conflict with his former master Obi-Wan Kenobi, and the two of them duelled over the blazing rivers of the volcanic world of Mustafar. In the end, Vader suffered a most painful defeat: his limbs were all severed by Obi-Wan's lightsaber and he was left to burn on the edge of a volcanic river bank. The flames seared his flesh, his face being horrifically scarred and his organs roasted. Only his connection to the Force and his overwhelming hatred of his former master kept him alive long enough for the Emperor to find him and return him to Coruscant so that he could be 'healed'. Upon his return, Vader's amputated limbs were replaced with mechanical prosthetics, his body encased in a cybernetic armoured suit that would provide him with life support, and a sinister-looking helmet and mask that would hide his disfigured face and assist with his breathing. As far as the Galaxy at large was concerned, Anakin Skywalker had died in battle during the war. No one apart from a few Jedi renegades would ever know that Anakin was lost behind the mask of Darth Vader.
For the next two decades, Darth Vader would serve Emperor Palpatine as the Galactic Empire's most lethal enforcer, hunting down any potential threat's to Palpatine's rule and enslaving whole populations to build the Empire's war machine. In the later years of the Galactic Civil War, Vader would discover his former master Obi-Wan to be still alive and would slay him aboard the Death Star battle station. He would also discover that he had a living offspring, Luke Skywalker, whom the Emperor demanded should be converted to the dark side of the Force. Vader fought against his son Luke in Cloud City on Bespin, slicing off the boy's hand and revealing to him their blood ties. Sensing that Luke possessed the potential to threaten the Emperor, Vader tried to sway Luke into joining him in overthrowing the Empire. Luke refused Vader's offer and made his escape, but father and son would meet again during the Civil War's final battle at Endor, aboard the Death Star II. Emperor Palpatine tried to awaken Luke's dark side power by pitting him and Vader against each other in combat. Whilst Vader tried to convince Luke to give in to hatred and anger, Luke tried to convince Vader to let go of his own. Deep down, Vader was stirred by his son's words, but their fight would continue until Luke had Vader cornered, a hand severed, and his son's lightsaber at his throat. Both warriors of the Force stood upon the line between light and darkness and the Emperor urged Luke to deal the killing blow and then take his father's place at Palpatine's side. Again, Luke refused, and so Palpatine took it upon himself to kill the young Jedi. As Darth Vader watched while the Emperor wracked Luke's body with a constant stream of Sith lightning, whatever remnant of the Jedi Knight Anakin Skywalker resurfaced. Vader then lunged at the Emperor, holding him high even as the old man's lightning cascaded down upon him, and then threw him down an air shaft. The bombardment of Force lightning and the Emperor's death spelled Darth Vader's death knells, and Anakin Skywalker asked his son Luke to remove the mask that hid his scarred face. The newly-unmasked Anakin told Luke to flee the doomed Death Star, stating that Luke had already saved him by bringing him back to the light side of the Force. He then died in his son's arms, who took his body off the station before it exploded. Darth Vader's armour was taken to Endor and was burned on a ceremonial pyre, as is traditional for a Jedi.
Darth Vader's injuries on Mustafar were so severe that he could never be fully healed, and so the Emperor had him sealed inside an armoured life-support suit to keep him alive and functional. The armour provides significant protection from blasters and a control panel on the torso allows Vader to regulate his life-support functions. The suit is not high quality, however, as parts of the cybernetic harness dig into Vader's flesh, causing him pain additional to what he already feels. The suit and Vader's robotic arms and legs are bulky and heavy, severely restricting his movement. Because of his cybernetics, Vader cannot tap into his full Force potential. He has never been able to produce Sith lightning and even if he could, his mechanics would conduct the electricity and kill him. Despite the cumbersome nature of his suit, Vader still possesses a great deal of Force abilities and his lightsaber skills remain sharp.