How Did Anakin Become Darth Vader?

Anakin Skywalker became Darth Vader in two steps, both in Revenge of the Sith. First he turned: to save his wife Padmé from the death he saw in his visions, he helped Palpatine against Mace Windu, knelt to him as Darth Sidious and was given the name Darth Vader. Then he lost his body: Obi-Wan Kenobi cut off his legs and remaining arm on Mustafar and left him burning, and Palpatine had what was left rebuilt inside the black armour. (Revenge of the Sith)

Step one: the fall#

The fear started with his mother. Anakin dreamed she was in pain, went back to Tatooine and found her dying among the Tusken Raiders. Afterwards he told Padmé he would become powerful enough to stop people dying. (Attack of the Clones)

In Revenge of the Sith the dreams return, this time of Padmé dying in childbirth. Palpatine, his friend since boyhood, tells him the story of Darth Plagueis, a Sith Lord who could keep the ones he cared about from dying, and then admits he is a Sith himself. The full story of that pull is on why Anakin turned to the dark side. (Revenge of the Sith)

Anakin does report him. But when he reaches Palpatine's office, Windu has the Chancellor beaten and is about to kill him. Anakin cuts off Windu's hand, Palpatine throws Windu out of the window with Force lightning, and Anakin kneels. He pledges himself to Sidious's teachings, asking only for help saving Padmé. Sidious tells him: "Henceforth you shall be known as... Darth... Vader." (Revenge of the Sith)

His first orders as Vader#

Sidious sends him straight to the Jedi Temple and tells him to show no mercy: only then will he be strong enough with the dark side to save Padmé. Vader leads the attack in which the Temple's Jedi, younglings included, are killed. The page on why Anakin killed the younglings covers that night. (Revenge of the Sith)

Next he goes to Mustafar and kills the Separatist leaders. When Padmé arrives and begs him to run away with her, he sees Obi-Wan on her ship, decides she has betrayed him and chokes her. To Obi-Wan he says he has brought peace, freedom, justice and security to his new Empire. (Revenge of the Sith)

Step two: Mustafar and the suit#

The duel ends on the bank of a lava river. Anakin tries to leap over Obi-Wan, who cuts off both his legs and his left arm. "You were the Chosen One!" Obi-Wan cries, and Anakin screams back, "I hate you!" Then the heat sets him on fire, and Obi-Wan leaves him. (Revenge of the Sith)

Palpatine senses something is wrong and flies to Mustafar. His troopers find Anakin still alive and get him into a medical capsule. On Coruscant, droids graft on new limbs and seal him into the armour, mask and breathing system. His first words as the Vader of the films are "Yes, Master", and his first question is about Padmé. Sidious tells him, "It seems, in your anger, you killed her." How Anakin survived Mustafar goes through it in detail. (Revenge of the Sith)

How the saga describes the change#

Obi-Wan's version to Luke is that Vader was seduced by the dark side of the Force. In Return of the Jedi he goes further: Anakin "ceased to be Anakin Skywalker... and became Darth Vader", and is now "more machine now than man... twisted and evil". (A New Hope; Return of the Jedi)

Vader tells it the same way. In Obi-Wan Kenobi, ten years after Mustafar, he refuses to be Obi-Wan's failure: "You didn't kill Anakin Skywalker. I did." (Obi-Wan Kenobi, "Part VI")

Interpretation: that is the key to the question. Becoming Vader wasn't just a new name or a new body. In his own mind, Anakin was a person he had killed. Return of the Jedi proves him wrong, when he turns on the Emperor to save Luke and dies as Anakin again. (Obi-Wan Kenobi, "Part VI"; Return of the Jedi)

Canon and Legends#

Both continuities start from the same films, so the core answer is the same in canon and Legends. (Revenge of the Sith)

Legends added more about the first months after Mustafar. In James Luceno's novel Dark Lord: The Rise of Darth Vader, Sidious admits he hadn't bargained for an apprentice who was more machine than man, but believes Vader's power is held back less by his injuries than by his own despair, and that he could recover it if he ever faced his choices. (Dark Lord: The Rise of Darth Vader)

Read more#

Anakin Skywalker and Darth Vader cover his whole life. For the injuries that made the mask necessary, see what happened to Anakin's face.