Anakin Skywalker was a legendary male Human Jedi Knight in the waning days of the Jedi Order who was believed to be the Chosen One. During his training, he was slowly swayed to the dark side of the Force by his many emotions and, most influentially, by the Sith Lord Darth Sidious. He eventually took on the mantle of Dark Lord of the Sith, thus becoming Darth Vader shortly before the formation of the Galactic Empire.
He was the son of Shmi Skywalker and the husband of Senator Padmé Amidala, as well as the father of Luke Skywalker and Leia Organa Solo.
After Jedi Master Qui-Gon Jinn discovered nine-year-old Anakin on Tatooine, he took him away from the planet to be trained in the ways of the Force, believing the boy to be the Chosen One of Jedi prophecy. Young Anakin was apprenticed to Obi-Wan Kenobi upon Qui-Gon's death.
Before becoming Vader, Skywalker served as a General (originally Commander) in the Grand Army of the Republic during the Clone Wars. As Vader, he was appointed to the role of Military Executor of Palpatine's New Order, and gained infamy as one of the Galaxy's greatest mass murderers. He also headed the Great Jedi Purge—a hunt for the remaining Jedi after Order 66.
In 4 ABY, at the Battle of Endor, he was redeemed by his son, and renounced the ways of the Sith, becoming Anakin Skywalker once again, moments before his death.
"He is the Chosen One. You must see it."
―Qui-Gon Jinn to the Jedi High Council
"Anakin, this path has been placed before you. The choice is yours alone."
―Shmi Skywalker
"The boy has exceptional skills."
"But he still has much to learn, Master. His abilities have made him… well, arrogant."
―Mace Windu and Obi-Wan Kenobi
"Remember, Obi-Wan, if the prophecy is true, your apprentice is the only one who can bring the Force back into balance."
―Mace Windu
"Sometimes a Jedi's most important duty is to stand and wait. I presume you've mentioned that to Anakin on occasion?"
"Not more than twice a day."
―Mace Windu and Obi-Wan Kenobi
"Ani?… My goodness, you've grown."
―Padmé Amidala to Anakin
"You're asking me to be rational. That is something that I know I cannot do. Believe me, I wish I could just wish away my feelings, but I can't."
―Anakin Skywalker
"Why'd she have to die? Why couldn't I save her? I know I could have!"
"Sometimes there are things no one can fix. You're not all powerful, Ani."
"Well I should be! Some day I will be. I will be the most powerful Jedi ever! I promise you. I will even learn to stop people from dying!"
"Anakin…"
"It's all Obi-Wan's fault! He's jealous! He's holding me back!"
―Anakin Skywalker and Padmé Amidala
"You're going to pay for all the Jedi that you've killed today, Dooku."
―Anakin Skywalker
"You are strong and wise, Anakin, and I am very proud of you. I have trained you since you were a small boy. I have taught you everything I know, and you have become a far greater Jedi than I could ever hope to be."
―Obi-Wan Kenobi
"I'm going to make you pay for what you've done."
"Come, Padawan. Your fall will be my ascension to the Sith."
―Anakin Skywalker and Asajj Ventress
"Soon I will have a new apprentice… one far younger and more powerful."
―Darth Sidious
"You die in childbirth."
"And the baby?"
"I don't know."
"It was only a dream."
"I won't let this one become real."
―Anakin Skywalker and Padmé Amidala
"Twisted by the dark side, young Skywalker has become. The boy you trained, gone he is… consumed by Darth Vader."
―Yoda to Obi-Wan Kenobi
"The war is over! Lord Sidious promised us peace! We only want—"
―Nute Gunray, just before Vader killed him
"It's over, Anakin! I have the high ground!"
"You underestimate my power!"
"Don't try it!"
―Obi-Wan and Vader
"I hate you!"
"You were my brother, Anakin. I loved you!"
―Darth Vader and Obi-Wan Kenobi
"You don't know the power of the dark side. I must obey my Master."
―Vader to his son
"Palpatine's mailed fist, Dooku's successor, Maul's inheritor."
―Shadday Potkin
"What could you hate enough to destroy me?"
"Myself."
―Darths Maul and Vader
"I've been waiting for you, Obi-Wan. We meet again at last. The circle is now complete. When I left you I was but the learner; now I am the Master."
"Only a master of evil, Darth."
―Darth Vader and Obi-Wan Kenobi
"The son of Skywalker must not become a Jedi…"
"If he could be turned, he would become a powerful ally…"
―Palpatine and Darth Vader
Obi-Wan never told you what happened to your father."
"He told me enough! He told me you killed him."
"No. I am your father."
―Darth Vader and Luke Skywalker
"It is the name of your true self. You have only forgotten. I know there is good in you. The Emperor hasn't driven it from you fully. That was why you couldn't destroy me. That's why you won't bring me to your Emperor now."
―Luke Skywalker
"You were right… you were right about me. Tell your sister… You were right…"
―Anakin Skywalker's dying words
"Maybe Vader had died heroically, but ten minutes of contrition did not make up for years of atrocities."
―Leia Organa
"… A special destiny is not always something joyous, or easy to bear. My father had a special destiny, and see where it took him."
―Luke Skywalker
"Sometimes things must be broken in order to be rebuilt."
―Jacen Solo
"For Anakin, there is nothing more important than friendship. He is the most loyal man I've ever met—loyal beyond reason; in fact […] abstractions like peace don't mean much to him. He's loyal to people, not to principles. And he expects loyalty in return. He will stop at nothing to save me, for example, because he thinks I would do the same for him… because he knows I would do the same for him."
―Obi-Wan Kenobi
His death:
During this time, the Emperor, Darth Sidious, relentlessly attempted to lure Luke to the dark side, tormenting him with thoughts of the defeat of the Rebel Alliance and the death of his friends. However, Luke continued to attempt to restrain himself from fighting his father. Vader, who had been probing Luke's thoughts, discovered that besides Luke he also had a daughter: Leia Organa, Luke's twin sister. Vader, happy at the finding, decided to use this knowledge against Luke, threatening to corrupt Leia. Luke, enraged, ignited his lightsaber and viciously attacked Vader with anger and hatred, slowly converting to the dark side. Finally, Luke sliced off Vader's mechanical right hand, defeating the Dark Lord. Palpatine, cackling with triumph, urged Luke to fulfill his destiny, and take his father's place at the Dark Lord's side. Vader then realized that he had been betrayed, just as Count Dooku had been betrayed decades previous.
Luke looked down to see his father's right severed arm, and, seeing that it was mechanical like his, he realized that he was about to become Vader's successor. Horrified at what he was about to do, Luke used a combination of Obi-Wan's teachings and the light side of the Force to calm himself down. Luke tossed his lightsaber away, refusing the Emperor's offer to join him as his new apprentice, declaring that he was a Jedi like his father before him. Enraged at the failure of his plans, the Emperor unleashed a barrage of Force lightning attacks upon Luke. Defiant in the face of evil, Luke suffered the wrath of Palpatine, and Vader could do no more than watch as Luke Skywalker lay dying.
But Anakin never forgot the pain Count Dooku had once inflicted upon him with the lethal power of Force lightning, and could not bear to see his son in such agony. He had been unable to save his mother, he had let Mace Windu die under his Master's power many years before, he had murdered hundreds of Jedi, he had lost his best friend, and he had killed his own wife and ensured his own downfall, but he could save his son. Anakin Skywalker would not stand by and let his son fall. From this moment on, Vader ceased to exist, and Anakin Skywalker was reborn. In a final heroic effort of self-sacrifice, rectifying his mistake by not helping Windu kill Palpatine before, Anakin reemerged from the mind of Vader and struggled to his feet to rescue his son from the Emperor. In an act out of pure love for his son, he literally overthrew his dark Master, completely lifting him off the ground with his great strength, and cast the Emperor down the Death Star's reactor shaft to his death. However, it was at the cost of his own life. Anakin was badly wounded in the process by the startled Emperor's flailing arms still issuing Force lightning, and his breathing apparatus short-circuited, but this single act served to redeem his past actions.
Luke, attempting to save Anakin's life, used Force-assisted strength to drag the dying, deadweight of Anakin's body to the hangar. Anakin, knowing that he would die whether or not Luke managed to get him onto a shuttle, stopped his son.
Nearing death, Anakin asked Luke to help him remove his mask, so that he could see his son with his own eyes, not through the blood red lens filters. Luke helped disconnect the mask and saw his father for the first time. Beneath, Anakin Skywalker was bald, his hair folicles having been incinerated in Mustafar's flames, and deathly pale, his skin having not seen sunlight for over two decades. However, his eyes were no longer the burning yellow they were, but a shining blue filled with the guilt and regret for his own sins. After seeing his son directly, he told Luke that he was right about him, as was his mother—there was good still in him; and to tell his sister, Leia, the same. With these last words, Anakin Skywalker died and became one with the Force.